To retrieve and deploy Salesforce Messaging Components, ConversationMessageDefinition should be used.

package.xml:

<?xml version="1.0" encoding="UTF-8"?>
<Package xmlns="http://soap.sforce.com/2006/04/metadata">
    <types>
        <members>*</members>
        <name>ConversationMessageDefinition</name>
    </types>
	<version>59.0</version>
</Package>