Refactor keyboard mode by enum

libs/hbb_common/protos/message.proto

@@ -97,6 +97,13 @@ message MouseEvent {
   repeated ControlKey modifiers = 4;
 }
 
+enum KeyboardMode{
+  Legacy = 0;
+  Map = 1;
+  Translate = 2;
+  Auto = 3;
+}
+
 enum ControlKey {
   Unknown = 0;
   Alt = 1;
@@ -190,7 +197,7 @@ message KeyEvent {
     string seq = 6;
   }
   repeated ControlKey modifiers = 8;
-  uint32 mode = 9;
+  KeyboardMode mode = 9;
 }
 
 message CursorData {