Add DeleteRequest and DeleteResponse to gRPC

Author: MatteoPologruto

rpc/cc/arduino/cli/settings/v1/settings.pb.go

@@ -36,6 +36,9 @@ service SettingsService {
 
   // Writes to file settings currently stored in memory
   rpc Write(WriteRequest) returns (WriteResponse);
+
+  // Deletes an entry and rewrites the file settings
+  rpc Delete(DeleteRequest) returns (DeleteResponse);
 }
 
 message GetAllResponse {
@@ -78,4 +81,13 @@ message WriteRequest {
   string file_path = 1;
 }
 
-message WriteResponse {}
+message WriteResponse {}
+
+message DeleteRequest {
+  // The key of the setting to delete.
+  string key = 1;
+  // Path to settings file (e.g. /path/to/arduino-cli.yaml)
+  string file_path = 2;
+}
+
+message DeleteResponse {}