* Make gala build against Mutter 3.32
* Add schemas override for Mutter 3.3x
* Fix Gala.WorkspaceManager.workspace_removed callback that cause a SIGABRT
* Fix Gala.WorkspaceManager.cleanup method which causes SIGABRT by trying to get non-existing workspaces
* Fix Gala.WorkspaceManager.cleanup method which deletes all workspace instead of keeping at least the last workspace
* Fix Multitasking-View remove_workspace callback which has an incorrect algorithm to remove destroyed workspaces
* Add missing manager.workspace_reordered callback for Mutter 3.34
