Fix Workspaces' hidden dependency on the path_alias module

This will also help with 📌 Make "path_alias" module optional Needs work where the (current) MR took a shortcut and made the dependency explicit.

Applied the MR on a standard Drupal install for 11.x
Uninstalled Path and installed Workspaces

Verified I can still use workspace normally jumping between spaces
Publishing content
etc

So since Workspace is still experimental I'm assuming no issue making core/modules/workspaces/src/EventSubscriber/WorkspaceRequestSubscriber.php internal

Yeah given both constructors and event subscribers are internal I think we can skip bc for that here.

Committed/pushed to 11.x and cherry-picked to 10.3.x, thanks!

Automatically closed - issue fixed for 2 weeks with no activity.