Mark conversation as unread

REQUIRED SCOPES <code>['conversations:write']</code><br> If you read a message, but want to take some time before addressing it, the message can be marked as unread. <br><br>This endpoint changes the status of messages in a given conversation to unread by the current user. Marking a message as unread displays the bold dot mark on the conversation in the conversation sidebar. <br><br>The message becomes grouped with all the other unread messages as the last_read_at field is set as empty.