In maintel/mtcs.py, add a context manager to ensure m1m3 is in engine…

…ering mode before/after some operation.

python/lsst/ts/observatory/control/maintel/mtcs.py

@@ -1707,6 +1707,22 @@ async def exit_m1m3_engineering_mode(self) -> None:
         else:
             self.log.warning("M1M3 not in engineering mode.")
 
+    @contextlib.asynccontextmanager
+    async def m1m3_in_engineering_mode(self) -> typing.AsyncIterator[None]:
+        """Context manager to ensure m1m3 enters and exists engineering
+        mode before/after an operation.
+
+        If M1M3 is in engineering mode before, this context manager is a
+        nop, e.g. it will leave M1M3 in engineering mode afterwards.
+        """
+        try:
+            m1m3_in_engineering_mode_before = await self.is_m1m3_in_engineering_mode()
+            await self.enter_m1m3_engineering_mode()
+            yield
+        finally:
+            if not m1m3_in_engineering_mode_before:
+                await self.exit_m1m3_engineering_mode()
+
     async def run_m1m3_hard_point_test(self, hp: int) -> None:
         """Test an M1M3 hard point.