[meta] Deprecate dependencies, libraries, modules, and themes that will be removed from Drupal 12 core

The very latest we can deprecate these modules is in the same minor release that comes out when 12.0.0 is released, but there are multiple steps involved before actual deprecation so it's really time to get this moving now.

Add issue for ArchiveTar

Wrong issue

search and shortcut has policy issues RTBC but stable9 and toolbar are blocked and not clear who can take a maintainer badge

Thanks for maintaining Drupal and trimming the core modules when needed.

Maybe we could consider adding a sentence about becoming contrib maintainer in each deprecate Drupal core module Meta issue?

As an example, in #3484850: [meta] Tasks to deprecate Toolbar module it could be something like below (the "Want to become a contrib maintainer ..." part):

Remaining tasks

1. Begin finding someone to maintain the contrib version of the extension.
   Want to become a contrib maintainer of this deprecated Drupal core module? Create an issue with the title "Offering to maintain Toolbar contrib module"
2. ...

ArchiverTar should also be removed and replaced by https://www.php.net/manual/en/class.phardata.php

• #3571185: Replace usage of \Drupal\Core\Archiver\ArchiveTar with \PharData and deprecate it
• #3027290: Use \Drupal\Core\Archiver\Tar instead of \Drupal\Core\Archiver\ArchiveTar in controllers are forms