feat(audio): add new audio assets and replace old wav files

1. add new mp3 format audio files and their meta configuration files
2. delete old unused wav format audio files and their meta files
3. add flash effect audio playback logic in skill casting system

assets/resources/music/BATTLE.mp3.meta

@@ -0,0 +1,14 @@
+{
+  "ver": "1.0.0",
+  "importer": "audio-clip",
+  "imported": true,
+  "uuid": "db35468f-265d-4465-86ba-5186c6c1d0a2",
+  "files": [
+    ".json",
+    ".mp3"
+  ],
+  "subMetas": {},
+  "userData": {
+    "downloadMode": 0
+  }
+}