This begins paving the way for removal of user access to kernel address space. After the previous commits, BDirectWindow and BWindowScreen still function properly. Part of #19990. Change-Id: I8477e43cd517ba67383755a4cb60b00bc117f5d7 Reviewed-on: https://review.haiku-os.org/c/haiku/+/10559 Reviewed-by: waddlesplash <[email protected]> Tested-by: Commit checker robot <[email protected]>