port clearpilot gpsd; decouple self-driving from GPS

Adds the AT-command-based GPS daemon for the Quectel EC25 modem (the
device has no u-blox chip and qcomgpsd's diag interface hangs on this
hardware). Trimmed from broken's version: dropped cloudlog calls and
the IsDaylight / ScreenDisplayMode auto-switching (those belong to the
display-modes feature, port later).

Used solely for system clock initialization, on-screen UI speed, and
per-segment dashcam GPS metadata.

Self-driving must NOT consume gpsLocation — feeding it to locationd's
kalman filter screws up the math. Patch locationd to skip GPS:
- locationd_thread() no longer subscribes to gpsLocation/gpsLocationExternal
- handle_msg's GPS branches commented (dead code without subscription)
- the "save LastGPSPosition once a minute when gpsOK" block commented
  (dead because gpsOK is now permanently false)

Result: liveLocationKalman.gpsOK = false for all self-driving consumers
(controlsd, paramsd, torqued, frogpilot_planner). They already handle
that case. Other liveLocationKalman fields still publish from the
camera-odometry + IMU + calibration kalman state.

system/clearpilot/__init__.py added so system.clearpilot.gpsd is a
valid Python module.

selfdrive/manager/process_config.py

@@ -82,6 +82,10 @@ procs = [
   PythonProcess("deleter", "system.loggerd.deleter", always_run),
   PythonProcess("dmonitoringd", "selfdrive.monitoring.dmonitoringd", driverview, enabled=(not PC or WEBCAM)),
   # PythonProcess("qcomgpsd", "system.qcomgpsd.qcomgpsd", qcomgps, enabled=TICI),  # Fixme
+  # CLEARPILOT: replacement for qcomgpsd (whose diag interface is broken on this device).
+  # Uses Quectel modem AT commands via mmcli. Self-driving does NOT consume this; locationd
+  # is patched to skip gpsLocation. Used only for system clock + UI speed + dashcam metadata.
+  PythonProcess("gpsd", "system.clearpilot.gpsd", qcomgps, enabled=TICI),
   # PythonProcess("ugpsd", "system.ugpsd", only_onroad, enabled=TICI),
   #PythonProcess("navd", "selfdrive.navd.navd", only_onroad),
   PythonProcess("pandad", "selfdrive.boardd.pandad", always_run),