vfs_ceph_new: Introduce new parametric option 'proxy'

vfs_ceph_new: Introduce new parametric option 'proxy'

Provide early support for consuming yet to come libcephfs proxy[1] for
optimized resource utilization. For better control we make use of an
additional module specific option 'proxy' to specify the intent to load
proxy library. With the default value 'no' a regular cephfs connection
is established. There is also an 'auto' mode which can fall back to the
regular connection if proxy requirements are not met.

[1] https://github.com/ceph/ceph/pull/58376

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15703

Signed-off-by: Guenther Deschner <gd@samba.org>
Reviewed-by: Guenther Deschner <gd@samba.org>