Backport fscache/cachefiles rework for 9.2

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1229736 Conflicts: Quite a few, but mostly in areas of code that aren't built for centos

This contains a pile of patches that rip out the old fscache and cachefiles codebase and adds the new. In addition, it pulls in the relevant patches for NFS, CIFS and Ceph to make use of the new cache API.

I also brought in quite a few patches for 9p and AFS. We don't ship those bits in RHEL9, but doing so made everything merge much more cleanly.

Signed-off-by: Jeffrey Layton jlayton@redhat.com