How to add Custom Component in the Embedded Chat Service

<aura:component implements="lightningsnapin:prechatUI" description="Sample custom pre-chat component for Embedded Chat. Implemented using Aura.">
    <!-- You must implement "lightningsnapin:prechatUI" for this component to appear in the "Pre-chat Component" customization dropdown in the Embedded Service setup -->

    <!-- Pre-chat field components to render -->
    <aura:attribute name="prechatFieldComponents" type="List" description="An array of objects representing the pre-chat fields specified in pre-chat setup."/>
    
    <!-- Handler for when this component is initialized -->
    <aura:handler name="init" value="{!this}" action="{!c.onInit}" />

    <!-- For Aura performance -->
    <aura:locator target="startButton" description="Pre-chat form submit button."/>
    
    <!-- Contains methods for getting pre-chat fields, starting a chat, and validating fields -->
    <lightningsnapin:prechatAPI aura:id="prechatAPI"/>
    
    <h2>Prechat form</h2>
    <div class="prechatUI">
        <div class="prechatContent">
            <ul class="fieldsList">
                <!-- Look in the controller's onInit function. This component dynamically creates the pre-chat field components -->
                {!v.prechatFieldComponents}
            </ul>
        </div>
        <div class="startButtonWrapper">
            <ui:button aura:id="startButton" class="startButton" label="{!$Label.LiveAgentPrechat.StartChat}" press="{!c.handleStartButtonClick}"/>
        </div>
    </div>

</aura:component>

({
    /**
     * On initialization of this component, set the prechatFields attribute and render pre-chat fields.
     * 
     * @param cmp - The component for this state.
     * @param evt - The Aura event.
     * @param hlp - The helper for this state.
     */
	onInit: function(cmp, evt, hlp) {
        // Get pre-chat fields defined in setup using the prechatAPI component
		var prechatFields = cmp.find("prechatAPI").getPrechatFields();
        // Get pre-chat field types and attributes to be rendered
        var prechatFieldComponentsArray = hlp.getPrechatFieldAttributesArray(prechatFields);
        
        // Make asynchronous Aura call to create pre-chat field components
        $A.createComponents(
            prechatFieldComponentsArray,
            function(components, status, errorMessage) {
                if(status === "SUCCESS") {
                    cmp.set("v.prechatFieldComponents", components);
                }
            }
        );
    },
    
    /**
     * Event which fires when start button is clicked in pre-chat
     * 
     * @param cmp - The component for this state.
     * @param evt - The Aura event.
     * @param hlp - The helper for this state.
     */
    handleStartButtonClick: function(cmp, evt, hlp) {
        hlp.onStartButtonClick(cmp);
    }
});

({
    /**
	 * Map of pre-chat field label to pre-chat field name (can be found in Setup)
	 */
    fieldLabelToName: {
        "First Name": "FirstName",
        "Last Name": "LastName",
        "Email": "Email",
        "Subject": "Subject",
        "Web Name": "SuppliedName",
        "Web Email": "SuppliedEmail"
    },
    
    /**
	 * Event which fires the function to start a chat request (by accessing the chat API component)
	 *
	 * @param cmp - The component for this state.
	 */
    onStartButtonClick: function(cmp) {
        var prechatFieldComponents = cmp.find("prechatField");
        var fields;
        
        
        // Make an array of field objects for the library
        fields = this.createFieldsArray(prechatFieldComponents);
        
        // If the pre-chat fields pass validation, start a chat
        if(cmp.find("prechatAPI").validateFields(fields).valid) {
            cmp.find("prechatAPI").startChat(fields);
        } else {
            console.warn("Prechat fields did not pass validation!");
        }
    },
    
    /**
	 * Create an array of field objects to start a chat from an array of pre-chat fields
	 * 
	 * @param fields - Array of pre-chat field Objects.
	 * @returns An array of field objects.
	 */
    createFieldsArray: function(fields) {
        if(fields.length) {
            return fields.map(function(fieldCmp) {
                return {
                    label: fieldCmp.get("v.label"),
                    value: fieldCmp.get("v.value"),
                    name: this.fieldLabelToName[fieldCmp.get("v.label")]
                };
            }.bind(this));
        } else {
            return [];
        }
    },
    
    /**
     * Create an array in the format $A.createComponents expects
     * 
     * Example:
     * [["componentType", {attributeName: "attributeValue", ...}]]
     * 
	 * @param prechatFields - Array of pre-chat field Objects.
	 * @returns Array that can be passed to $A.createComponents
     */
    getPrechatFieldAttributesArray: function(prechatFields) {
        // $A.createComponents first parameter is an array of arrays. Each array contains the type of component being created, and an Object defining the attributes.
        var prechatFieldsInfoArray = [];
        
        // For each field, prepare the type and attributes to pass to $A.createComponents
        prechatFields.forEach(function(field) {
            
            var componentName = (field.type === "inputSplitName") ? "inputText" : field.type;
            var componentInfoArray = ["ui:" + componentName];
            var attributes = {
                "aura:id": "prechatField",
                required: field.required,
                label: newLabel,
                disabled: field.readOnly,
                maxlength: field.maxLength,
                class: field.className,
                value: field.value
            };
            
            // Special handling for options for an input:select (picklist) component
            if(field.type === "inputSelect" && field.picklistOptions) attributes.options = field.picklistOptions;
            
            // Append the attributes Object containing the required attributes to render this pre-chat field
            componentInfoArray.push(attributes);
            
            // Append this componentInfoArray to the fieldAttributesArray
            prechatFieldsInfoArray.push(componentInfoArray);
        });
        
        return prechatFieldsInfoArray;
    }
});

<style type='text/css'>
	.embeddedServiceHelpButton .helpButton .uiButton {
		background-color: #005290;
		font-family: "Arial", sans-serif;
	}
	.embeddedServiceHelpButton .helpButton .uiButton:focus {
		outline: 1px solid #005290;

	}
    .embeddedServiceSidebarState.stateBody {
    width: 100%;
    height: 100%;
    text-align: left;
	}
    .embeddedServiceSidebarFeature ul, .embeddedServiceSidebarFeature li{
    max-inline-size: min-content;
    margin-top: 16px;
    }
    .startButton.uiButton{
    position: absolute;
    top: 75%;
    left: 34%;
    }
</style>