Add um982_driver + gnss_comm (renamed from rtk_ws to fhd_rtk_ws)

UM982 RTK GNSS driver workspace used by the triple-camera scan GUI for
recording /ublox_driver/receiver_pvt alongside LiDAR/camera bags. Ported
from FAST-LIVO2-RTK-ROS2's um982_driver spec, adapted for this UM982
receiver instead of the original repo's GNSS module.

src/gnss_comm/msg/GnssPVTSolnMsg.msg

@@ -0,0 +1,22 @@
+# This message contains information of UBX-NAV-PVT message.
+# reference: [1]. UBX-18010854-R08, page 132
+
+GnssTimeMsg time    # GNSS time of the navigation epoch
+# GNSS fix type (0=no fix, 1=dead reckoning only, 2=2D-fix, 3=3D-fix,
+# 4=GNSS+dead reckoning combined, 5=time only fix)
+uint8   fix_type
+bool    valid_fix   # if fix valid (1=valid fix)
+bool    diff_soln   # if differential correction were applied (1=applied)
+uint8   carr_soln   # carrier phase range solution status (0=no carrier phase, 1=float, 2=fix)
+uint8   num_sv      # number of satellites used in the solution
+float64 latitude    # latitude [degree]
+float64 longitude   # longitude [degree]
+float64 altitude    # height above ellipsoid [m]
+float64 height_msl  # height above mean sea level [m]
+float64 h_acc       # horizontal accuracy estimate [m]
+float64 v_acc       # vertical accuracy estimate [m]
+float64 p_dop       # Position DOP
+float64 vel_n       # NED north velocity [m/s]
+float64 vel_e       # NED east velocity [m/s]
+float64 vel_d       # NED down velocity [m/s]
+float64 vel_acc     # speed accuracy estimate [m/s]