Comments Title: Displays the post type name as preview in the editor

[gigitux]

What problem does this address?

Currently, in the editor, the preview of the Comments Title is hard coded and it is Post Title. Instead of hardcoding Post Title, rendering the post type name in the preview would improve the user experience.

For instance, in the image below, I'm editing the Single Template for the post type Movie. The Comments Title Block should show Movie Title instead of Post Title.

This issue is part of #49108