Add new music tracks to the sound directory

- Added cosmic_unicorns.ogg
- Added funky_eldritch.ogg
- Added meditative_beings.ogg
- Added owniverse_main_theme.ogg

These tracks enhance the audio experience of the project.

tests/benchmark_saved_state.gd

@@ -22,8 +22,8 @@ func run():
         quit(1)
         return
     var data = JSON.parse_string(FileAccess.get_file_as_string(args[0]))
-    if not data is Dictionary or data.get("format_version") != 3:
-        push_error("Expected diagnostic JSON format 3")
+    if not data is Dictionary or data.get("format_version") != 4:
+        push_error("Expected diagnostic JSON format 4")
         quit(1)
         return
     var initial: Dictionary = E.decode(restore_json_integers(data)).state