mds: allow all types of MDS caps

mds: allow all types of MDS caps

MDS caps can contain 5 components: name of a CephFS, a path inside
CephFS, a flag for enabling root squashing mechanism, a UID and list of
GIDs. These 5 components result in 31 combinations, so there can be 31
types of MDS caps. Out of these, the current main branch only allows 11
combinations. This restriction is strange and inappropriate. Ideally,
all combinations should be allowed.

This strange restriction must've been created unintentionally by
previous developers while adding FS name and root squash to MDS caps. A
TODO for a allowing a subset of these combination was also left in
codebase:
https://github.com/ceph/ceph/blob/reef/src/mds/MDSAuthCaps.cc#L69

Fixes: https://tracker.ceph.com/issues/59388
Signed-off-by: Rishabh Dave <ridave@redhat.com>
(cherry picked from commit 0c36929f258f2b32ded16bfaf40f99c27b668f44)

Conflicts:
	src/mds/MDSAuthCaps.cc
	- Unlike main branch, in Reef branch, string was being used in
	  the conflicted code by writing std::string.