feat: Add session bus option for local testing and development

Introduced a `--use-session-bus` flag to optionally use the D-Bus
session bus instead of the system bus. This allows better flexibility
for local testing and development scenarios without requiring
system-level changes. Updated related classes and functions to respect
the new flag.

src/revpi_middleware/proginit.py

@@ -9,7 +9,7 @@ __version__ = "1.4.0"
 
 import logging
 import sys
-from argparse import ArgumentParser, Namespace
+from argparse import ArgumentParser, Namespace, SUPPRESS
 from configparser import ConfigParser
 from enum import Enum
 from os import R_OK, W_OK, access, environ, getpid, remove
@@ -262,6 +262,16 @@ parser = ArgumentParser(
     prog=programname,
     description="Program description",
 )
+
+# Use session bus of D-Bus for local testing and development proposes (hidden)
+parser.add_argument(
+    "--use-session-bus",
+    dest="use_session_bus",
+    action="store_true",
+    default=False,
+    help=SUPPRESS,
+)
+
 parser.add_argument("--version", action="version", version=f"%(prog)s {program_version}")
 parser.add_argument(
     "-f",