Introducing the sidebar inspector block tools tabs

[priethor]

Now that block tools are more clearly delineated, ​this feature splits the block inspector between settings and appearance using a tabbed interface.

This feature is required for the Navigation off canvas editing feature introduced in #57653.

[priethor]

I'd like to propose blessing this feature be blessed for the 6.2 release cycle:

• It was stabilized and became the default experience in ​Gutenberg 15.0.
• There were many accessibility-related discussions, and might need follow-ups in that regard.

[hellofromTonya]

There is a discussion underway in ​in Core Slack core-committers channel for code being copied/merged from Gutenberg into Core already being blessed.

Today is 6.2 Beta 1. Core's handbook is clear about how to handle ALL enhancements and features requests before starting Beta 1.

• ​How the Release Cycle Works:

  Phase 3: Beta. Betas are released and beta-testers are asked to start reporting bugs. No more commits for new enhancements or feature requests are allowed for the rest of the release.
  

• ​Releasing Beta and RC Versions:

  For Beta releases, ensure that the milestone is cleared of enhancement and feature request tickets (e.g., Trac query for 6.1). If there is agreement within the release squad that a certain enhancement or feature request is critical for the release and thus needs to remain in the milestone, its ticket type should be changed to “Task (blessed)”. Also ensure with the Editor Tech Lead that enhancements/features merges from Gutenberg are similarly either cleared from the milestone or changed to a “Task (blessed)”.
  

This discussion likely will not get resolved before today's Beta 1 party starts.

I'm setting this new feature to "blessed" as it is planned for 6.2 and has already been released in Gutenberg. Its continuation is feature refinement. Given the fast iterations and release cycles, it will receive more testing, discussion, and feedback through Gutenberg's cycles than in Core's beta cycle.

This "blessed" feature can be revisited once there's resolution to the discussion.

In talking with @priethor, there will be a mixture of PHP code to merge/backport and packages to update. This ticket can be the landing place to track the feature.

[hellofromTonya]

The individual commits made for this enhancement need to be copied here from the @wordpress package updates #57471. That'll wire the changes to the feature.

As RC1 is happening in a few hours, closing this ticket.