Create SoundAsset in project.proto

proto/src/main/proto/project.proto

@@ -13,6 +13,7 @@ message Project {
   repeated FontAsset fonts = 7;
   repeated WidgetAsset widgets = 8;
   repeated AnimationAsset animations = 9;
+  repeated SoundAsset sounds = 10;
 }
 
 message GameMapAsset {
@@ -62,3 +63,9 @@ message AnimationAsset {
   required uint32 rows = 4;
   required uint32 columns = 5;
 }
+
+message SoundAsset {
+  required string uid = 1;
+  required string source = 2;
+  required string name = 3;
+}