[meta] Requirements for tagging 11.0.0

Must-haves

• Drupal will let you "upgrade" from 10.4.0 to 11.0.0, but that's actually a downgrade. Needs both longterm meta and immediate hotfix hack for 11.0.0 to prevent the downgrade (even with bad UX, going through an upgrade that's a downgrade where you have to upgrade more things is worse UX, and undercuts the core principles of the D8+ release philosophy):

  #3463225: [meta] Prevent 'downgrades' from maintenance minors to older minor releases for the next major version

• #3331950: 11.0.0 release notes
• Address any regressions in previous milestones.
• Address any straggler deprecation cleanups
• Resolve critical 10.x -> 10.x upgrade path bugs.
• Resolve any 11.0.x-only security or data integrity issues.
• Resolve other D11-only upgrade blockers.

Should-haves

• #3456244: Normalize the incoming path with urldecode directly in RouteProvider
• #3458177: Changing plugins from annotations to attributes in contrib leads to error if plugin extends from a missing dependency
• #3463954: Bump phpstan/phpstan to latest to make daily "updated deps" QA run pass again
• #3465166: Update JavaScript dependencies for Drupal 11.0.0