mgr: add mgr_subinterpreter_modules config

mgr: add mgr_subinterpreter_modules config

This commit adds a mgr_subinterpreter_modules config to cause specified
modules (or all if * is specified) to be loaded in individual
subinterpreters.

This changes the default behavior of ceph-mgr from running each module
in a distinct subinterpreter to running them all in the same main
interpreter.  We can reintroduce subinterpreter support over time by
adding modules to the list as we test them.

Fixes: https://tracker.ceph.com/issues/73857
Fixes: https://tracker.ceph.com/issues/73859
Signed-off-by: Samuel Just <sjust@redhat.com>
(cherry picked from commit 239b0dc8a9c42449ee1faa1bf78bdcc380345ae2)

Conflicts:
  - src/mgr/PyModule.cc
     #include "common/JSONFormatter.h" - removed (missing commit 3ab70dd in tentacle), not in tentacle
     dtor - still missing commit 3366ef5 on tentacle causing conflicts,
      taking tentacle changes with use_main_interpreter and end the interpater pMyThreadState.ts