Add a Notes column to the posts list table

[lukecarbis]

The list of posts could include a column for Notes.

In the future, this could be expanded to include unread notes.

In order to accommodate this, the current comments Dashicon in table header should be replaced by a simple "Comments" label.

[lukecarbis]

mockup of a comments and notes column next to each other in the posts list table

• Adds a new column to the posts list table for Notes.
• Changes the header for the Comments column to text instead of an icon
• Add sub-feature support to the post_type_supports function

Trac ticket: https://core.trac.wordpress.org/ticket/64377

[westonruter]

I seem to remember this having been discussed before, but I can't remember when/where.

[JeffPaul]

This was previously explored in ​https://github.com/WordPress/gutenberg/issues/71622, with the rationale for removing the column noted in ​https://github.com/WordPress/gutenberg/issues/71622#issuecomment-3355185451.

Before further reviews/approval here, will want to check back on ​https://github.com/WordPress/gutenberg/issues/71622#issuecomment-3355185451 where this was previously rejected as a concept.