msg ROS2 compatibility, microdds_client improvements (timesync, reduced code size, added topics, etc), fastrtps purge

- update all msgs to be directly compatible with ROS2
 - microdds_client improvements
   - timesync
   - reduced code size
   - add to most default builds if we can afford it
   - lots of other little changes
 - purge fastrtps (I tried to save this multiple times, but kept hitting roadblocks)

msg/FollowTarget.msg

@@ -0,0 +1,11 @@
+uint64 timestamp  # time since system start (microseconds)
+
+float64 lat       # target position (deg * 1e7)
+float64 lon       # target position (deg * 1e7)
+float32 alt       # target position
+
+float32 vy        # target vel in y
+float32 vx        # target vel in x
+float32 vz        # target vel in z
+
+uint8 est_cap     # target reporting capabilities