Add warnings when calling deprecated method (#596)

* Add test

* To run the workflow

* Fix import

* Format

* Add warning

* Fix indentation

* Test deprecated method

* More test

* Format

* Add import if needed

---------

Co-authored-by: Adrien Vannson <adrien.vannson@gardacp.com>

tests/inputs/deprecated/deprecated.proto

@@ -12,3 +12,10 @@ message Message {
     option deprecated = true;
     string value = 1;
 }
+
+message Empty {}
+
+service TestService {
+    rpc func(Empty) returns (Empty);
+    rpc deprecated_func(Empty) returns (Empty) { option deprecated = true; };
+}