ekf2: estimator aid source status (starting with fake position)

msg/estimator_aid_source_2d.msg

@@ -0,0 +1,22 @@
+uint64 timestamp             # time since system start (microseconds)
+uint64 timestamp_sample      # the timestamp of the raw data (microseconds)
+
+uint8 estimator_instance
+
+uint32 device_id
+
+uint64[2] time_last_fuse
+
+float32[2] observation
+float32[2] observation_variance
+
+float32[2] innovation
+float32[2] innovation_variance
+float32[2] test_ratio
+
+bool[2] fusion_enabled       # true when measurements are being fused
+bool[2] innovation_rejected  # true if the observation has been rejected
+bool[2] fused                # true if the sample was successfully fused
+
+# TOPICS estimator_aid_source_2d
+# TOPICS estimator_aid_src_fake_pos