autotest: add load_generic_mission

Tools/autotest/Generic_Missions/flaps.txt

@@ -0,0 +1,13 @@
+QGC WPL 110
+0	0	0	16	0.000000	0.000000	0.000000	0.000000	-35.363262	149.165237	584.390015	1
+1	0	3	22	15.000000	0.000000	0.000000	0.000000	-35.361279	149.164230	30.000000	1
+2	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.361229	149.163025	80.000000	1
+3	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.364563	149.163773	80.000000	1
+4	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.364384	149.164795	80.000000	1
+5	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.361027	149.164093	80.000000	1
+6	0	0	177	2.000000	3.000000	0.000000	0.000000	0.000000	0.000000	0.000000	1
+7	0	3	189	0.000000	0.000000	0.000000	0.000000	-35.362915	149.162613	60.000000	1
+8	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.363136	149.162750	60.000000	1
+9	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.365467	149.164215	55.000000	1
+10	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.365009	149.165482	39.889999	1
+11	0	3	21	0.000000	0.000000	0.000000	1.000000	-35.363041	149.165222	0.000000	1

Tools/autotest/common.py

@@ -3297,6 +3297,12 @@ class AutoTest(ABC):
     def load_sample_mission(self):
         self.load_mission(self.sample_mission_filename())
 
+    def load_generic_mission(self, filename, strict=True):
+        return self.load_mission_from_filepath(
+            os.path.join(testdir, "Generic_Missions"),
+            filename,
+            strict=strict)
+
     def load_mission(self, filename, strict=True):
         return self.load_mission_from_filepath(
             self.current_test_name_directory,