Replace Post/Block tab switcher with TabPanel

[mirka]

Prerequisite for #41904 #42320

The Post/Block tab switcher in the Inspector (.edit-post-sidebar__panel-tabs) is currently implemented as a list of buttons, and is missing tabpanel semantics.

This should be replaced with the TabPanel component.

[talldan]

I found this old PR that attempted to do this, but was closed - Use TabPanel in edit settings sidebar header (#13587).

It looks like one issue surfaced in that PR (and has come up a few times recently in other issues) is that TabPanel may have to become a controlled component. I think when you deselect a block the selected tab changes from 'Block' to 'Post'.

[mirka]

It looks like one issue surfaced in that PR (and has come up a few times recently in other issues) is that TabPanel may have to become a controlled component.

Ah, #46704 may unblock it then.

[alexstine]

@aaronrobertshaw asked for my feedback over here in another issue.

I highly support this now that the TabPanel is working better than it ever has before. Cannot wait to see this happen. This will move us another step in the right direction of having consistent controls/interactions.

Thanks.

[mirka]

Closed by #55360