mon: MonCap: add new profiles

mon: MonCap: add new profiles

Adds three new profiles:

  read-only:  able to issue all read-only (MON_CAP_R) commands.  Any
  command that may take additional caps (MON_CAP_W or MON_CAP_X) won't
  be allowed.

  read-write: able to issue all read-write (MON_CAP_R | MON_CAP_W)
  commands.  Commands that require MON_CAP_X will not be allowed.

  role-definer: solely able to issue commands on the 'auth' subsystem,
  to which all caps are given (MON_CAP_R | MON_CAP_W | MON_CAP_X).

Fixes: #8899
Signed-off-by: Joao Eduardo Luis <joao.luis@inktank.com>