common/admin_socket: remove dead code

Signed-off-by: John Spray <john.spray@redhat.com>
mon: remove unused attribute notified_global_id

Signed-off-by: John Spray <john.spray@redhat.com>
client: include ID in mds_sessions asok

So that an admin can map a ceph-fuse process
reliably to an entry in the MDS session list.

Signed-off-by: John Spray <john.spray@redhat.com>
mds: add `session ls` and `session evict` to asok

These commands are intended to help admins deal
with MDSs during recovery, to identify troublesome
clients which may need intervention (such as eviction).

Signed-off-by: John Spray <john.spray@redhat.com>