Add warnings to sensor SensorState

This commit adds a new field `warnings` to the `SensorState` message in
the `sensors.proto` file. This field is a repeated field of type
`SensorDiagnostic`, which is used to represent warnings for the
microgrid sensor. The `warnings` field is expected to have warnings if
and only if the sensor is reporting warnings. The list will contain
unique members, meaning no warning will exist twice in this list.

This makes the `SensorState` message consistent with respect to
`ElectricalComponentState`.

Signed-off-by: Tiyash Basu <[email protected]>

Author: tiyash-basu-frequenz

RELEASE_NOTES.md

@@ -17,6 +17,7 @@
 - The enum `ComponentErrorCode` has now been renamed to `ElectricalComponentDiagnosticCode` to better reflect its shared usage with warnings and errors.
 - Added new message `SensorDiagnostic` to represent warnings and errors in microgrid sensors.
 - The enum `SensorErrorCode` has now been renamed to `SensorDiagnosticCode` to better reflect its shared usage with warnings and errors.
+- Added warnings to sensor `SensorState`.
 
 ## Bug Fixes
 

proto/frequenz/api/common/v1/microgrid/sensors/sensors.proto

@@ -193,6 +193,17 @@ message SensorState {
   //    this list.
   repeated SensorStateCode states = 2;
 
+  // List of warnings for the microgrid sensor.
+  //
+  // !!! note
+  //    This list is expected to have warnings if and only if the sensor is
+  //    reporting warnings.
+  //
+  // !!! note
+  //    The list will contain unique members. No warning will exist twice in
+  //    this list.
+  repeated SensorDiagnostic warnings = 3;
+
   // List of errors for the microgrid sensor.
   //
   // !!! note