Backport: Template and template parts updated labels

[ntsekouras]

In this Gutenberg PR: ​https://github.com/WordPress/gutenberg/pull/61146 we added the item_updated label to template and template parts labels. We need to back port this for the next release.

If you save/update a template in post editor right now, the notification message renders post updated. You can test this only with templates right now, since the editing of template parts in isolation in post editor will be available in the next release.

Trac ticket: https://core.trac.wordpress.org/ticket/61095#ticket

In this Gutenberg PR: ​https://github.com/WordPress/gutenberg/pull/61146 we added the item_updated label to template and template parts labels. We need to back port this for the next release.

If you save/update a template in post editor right now, the notification message renders post updated. You can test this only with templates right now, since the editing of template parts in isolation in post editor will be available in the next release.

[audrasjb]

Thanks for the ticket and patch!
Marking this as ready for commit and assigning to milestone 6.6.

[audrasjb]

In 58055:

Editor: Add item_updated label for wp_template and wp_template_part post types.

This adds the item_updated label to Template and Template Part post types registration. This prevents from displaying the default post updated label.
See ​https://github.com/WordPress/gutenberg/pull/61146

Follow-up to [52062], [51003].

Props ntsekouras, ellatrix.
Fixes #61095.

Merged to Core in https://core.trac.wordpress.org/changeset/58055

Thank you!