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/cli_commands/dbus_helper.py

@@ -5,8 +5,9 @@ from threading import Thread
 from time import sleep
 
 from gi.repository import GLib
-from pydbus import SystemBus
+from pydbus import SessionBus, SystemBus
 
+from .. import proginit as pi
 from ..dbus_middleware1 import REVPI_DBUS_BASE_PATH
 from ..dbus_middleware1 import REVPI_DBUS_NAME
 
@@ -34,7 +35,7 @@ def simple_call(method: str, *args, interface: str, object_path=REVPI_DBUS_BASE_
     Any
         The result of the method invocation on the targeted D-Bus interface.
     """
-    bus = SystemBus()
+    bus = SessionBus() if pi.pargs.use_session_bus else SystemBus()
     revpi = bus.get(REVPI_DBUS_NAME, object_path)
     iface = revpi[interface]
     return getattr(iface, method)(*args)
@@ -55,7 +56,7 @@ def await_signal(signal_name: str, timeout: int, interface: str, object_path=REV
         detected_signal = True
         loop.quit()
 
-    bus = SystemBus()
+    bus = SessionBus() if pi.pargs.use_session_bus else SystemBus()
     revpi = bus.get(REVPI_DBUS_NAME, object_path)
     iface = revpi[interface]