Patterns: Add UI to rename/delete pattern category in the Site Editor

[t-hamano]

Related to #54640

What problem does this address?

As far as I know, there is no UI in the Site Editor to rename or delete pattern categories once they have been created. The only way is to access wp-admin/edit-tags.php?taxonomy=wp_pattern_category directly, but only a few users will know this URL.

What is your proposed solution?

In the short term, we might want to add wp-admin/edit-tags.php?taxonomy=wp_pattern_category either above or below "Manage all of my patterns".

Personally, I think it would be ideal to be able to rename or delete categories from the Ellipsis dropdown.

[t-hamano]

Another option might be to display a dropdown menu at the top right of the canvas.