Site Editing: Add a "Template" tab in the Inspector when editing a template

[jameskoster]

When editing a template, it would be useful to have a "Template" tab in the inspector. For now this can just display the template details. In the future it can be a home for revisions (like posts), and other template settings / options.

Here's an exciting screenshot:

[paaljoachim]

A question comes up....
Do we want to have three tabs?
Post/Page - Block - Template

Clicking the Template tab would bring focus to template parts in the post or page one is in. (As a switcher.)

These tabs creates a shift in focus.
In the layout: Click outside any block and Post settings will automatically be selected.
In the sidebar: Click the Post tab and switch to the Post settings.

In the layout: Click a block and notice the automatic shift of focus over to the Block tab options.
In the sidebar: (When no block is selected) Click the Block tab and see the message no Block selected.

In the layout: Click the header/footer etc template and the sidebar tab could switch over to template.
In the sidebar: Click the Template tab and switch focus to site editing and template options.

The Post/Page settings could contain a more obvious shift between post/page <-> template focus.
Yes there is an edit template today, but it is not obvious how to bring focus back to the post content editing.

Clicking a block in the layout automatically switches the focus to the Block tab as that is associated with the block that is selected. Clicking the Template

[jameskoster]

One problem with that suggestion – imo – is that it doesn't create enough separation between the document (post/page) and template. If template details are accessible through a tab in the Inspector, I worry that users would perceive the template to be a part of the document somehow, rather than a separate entity in its own right.

I appreciate the desire to reduce friction, but sometimes I think a little friction can be good. It makes the user pause momentarily so that they can understand the scope of the exercise.

Yes there is an edit template today, but it is not obvious how to bring focus back to the post content editing.

We should perhaps discuss this in isolation, but in #27848 a "← Return to post" link is suggested when you move from editing a post to a template:

Keynote employs a similar pattern with their "Done" button that becomes visible when you edit a master slide. It works quite well:

[paaljoachim]

Yeah. Let's keep it to two tabs.

In template mode. The tabs:
Template - Block

The template panel could show some other options or additional options in the Status & visibility. As right now it becomes too similar to the same panel in the post editor screen. Thinking of which options would be natural to have more visible.