mgr: Add per-module performance counters to mgr

mgr: Add per-module performance counters to mgr

This commit introduces performance counters for individual Ceph mgr modules.
These counters allow monitoring module behavior, debugging latency issues,
and identifying performance bottlenecks, all without modifying the modules themselves.

The following counters are now exposed under:
  > ceph daemon mgr.<id> perf dump

Example structure:
"mgr_module_<module_name>": {
    "notify_avg_usec": {     <- Average time spent handling notify events
        "avgcount": 0,
        "sum": 0
    },
    "cmd_avg_usec": {        <- Average time spent processing CLI/admin commands
        "avgcount": 0,
        "sum": 0
    },
    "serve_avg_usec": {      <- Average time spent in module serve loop (if applicable)
        "avgcount": 0,
        "sum": 0
    },
    "alive": 1               <- Module is alive (1 = running, 0 = exited)
    "cpu_usage": 0,          <- CPU usage in percent
    "mem_rss_change": 0,     <- Memory RSS change in bytes
    "mem_rss_current": 490737664 <- Memory RSS current in bytes

}

Signed-off-by: Nitzan Mordechai <nmordech@ibm.com>
Conflicts:
  src/mgr/ActivePyModules.cc - finisher.queue changed by 63859, adding py_module to the parameter list
  src/mgr/PyModuleRegistry.cc - check_all_modules_started added by 63859