Feat CCT-965: Include timezone in the logs

In `subscription-manager/src/rhsm/logutil.py`i:

* New loggin formater class `RhsmISO8601Formatter` was made
to ensure that time stamp entry is in ISO-8810 format and
that it contains info about milliseconds and time zone.

* Then variable `LOG_FORMATTER` is made and `RhsmISO8601Formatter(LOG_FORMAT)`
is assigned to it. Then distributed to places where `.setFormatter(Formatter(LOG_FORMAT, ...))` occured.

CARD CCT-965

note.txt

@@ -0,0 +1,5 @@
+Today:
+  - detailed iteration of my mailbox -> finished some forgotten undone "formal" tasks (e.g. CITI card activation)
+  - CCT-965: finding out solution for impossibility to simply have microseconds rounded to millisecons and simultaneously time zone in log timestamp
+  - CSI retro & prioritization meetings
+

src/rhsm/logutil.py

@@ -16,6 +16,15 @@
 import os
 import sys
 import rhsm.config
+import datetime
+
+
+class RhsmISO8601Formatter(logging.Formatter):
+    """ Ensure date & time to be in ISO8601 format and containing info about milliseconds and time zone"""
+
+    def formatTime(self, record, datefmt=None):
+        return datetime.datetime.fromtimestamp(record.created).astimezone().isoformat(timespec='milliseconds')
+
 
 LOGFILE_DIR = "/var/log/rhsm/"
 LOGFILE_PATH = os.path.join(LOGFILE_DIR, "rhsm.log")
@@ -30,6 +39,8 @@
     "%(threadName)s @%(filename)s:%(lineno)d - %(message)s"
 )
 
+LOG_FORMATTER = RhsmISO8601Formatter(LOG_FORMAT)
+
 _rhsm_log_handler: Optional["RHSMLogHandler"] = None
 _subman_debug_handler: Optional["SubmanDebugHandler"] = None
 log: Optional[logging.Logger] = None
@@ -152,15 +163,15 @@ def _get_default_rhsm_log_handler() -> (
     error: Optional[Exception] = None
     if not _rhsm_log_handler:
         _rhsm_log_handler, error = RHSMLogHandler(LOGFILE_PATH, USER_LOGFILE_PATH)
-        _rhsm_log_handler.setFormatter(logging.Formatter(LOG_FORMAT))
+        _rhsm_log_handler.setFormatter(LOG_FORMATTER)
     return _rhsm_log_handler, error
 
 
 def _get_default_subman_debug_handler() -> Union[None, "SubmanDebugHandler"]:
     global _subman_debug_handler
     if not _subman_debug_handler:
         _subman_debug_handler = SubmanDebugHandler()
-        _subman_debug_handler.setFormatter(logging.Formatter(LOG_FORMAT))
+        _subman_debug_handler.setFormatter(LOG_FORMATTER)
     return _subman_debug_handler