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/LogMessage.msg

@@ -0,0 +1,8 @@
+# A logging message, output with PX4_{WARN,ERR,INFO}
+
+uint64 timestamp		# time since system start (microseconds)
+
+uint8 severity # log level (same as in the linux kernel, starting with 0)
+char[127] text
+
+uint8 ORB_QUEUE_LENGTH = 4