Implement working BGM player

Assets/Singleton/SingletonManager.prefab

@@ -44,7 +44,6 @@ MonoBehaviour:
   m_Script: {fileID: 11500000, guid: 253db048700363d419cdd2430bb39594, type: 3}
   m_Name: 
   m_EditorClassIdentifier: 
-  _player: {fileID: 6949365541298368387, guid: 6ebbe09c2673d744faf84db54d3d12ed, type: 3}
 --- !u!1 &3584299649024768175
 GameObject:
   m_ObjectHideFlags: 0
@@ -90,7 +89,6 @@ GameObject:
   m_Component:
   - component: {fileID: 3584299649035273204}
   - component: {fileID: 3584299649035273207}
-  - component: {fileID: 9052846114851158357}
   m_Layer: 0
   m_Name: BGM Manager
   m_TagString: Untagged
@@ -125,105 +123,7 @@ MonoBehaviour:
   m_Script: {fileID: 11500000, guid: 978ba66c51f1aa942bb951304a3dc54d, type: 3}
   m_Name: 
   m_EditorClassIdentifier: 
-  backgroundMusic:
-  - {fileID: 8300000, guid: 3b5765e9830162448a81b1ba84c5dd91, type: 3}
-  - {fileID: 8300000, guid: 7ec6116eaa70bb64d9b0e30763c77adb, type: 3}
---- !u!82 &9052846114851158357
-AudioSource:
-  m_ObjectHideFlags: 0
-  m_CorrespondingSourceObject: {fileID: 0}
-  m_PrefabInstance: {fileID: 0}
-  m_PrefabAsset: {fileID: 0}
-  m_GameObject: {fileID: 3584299649035273206}
-  m_Enabled: 1
-  serializedVersion: 4
-  OutputAudioMixerGroup: {fileID: 0}
-  m_audioClip: {fileID: 0}
-  m_PlayOnAwake: 1
-  m_Volume: 1
-  m_Pitch: 1
-  Loop: 0
-  Mute: 0
-  Spatialize: 0
-  SpatializePostEffects: 0
-  Priority: 128
-  DopplerLevel: 1
-  MinDistance: 1
-  MaxDistance: 500
-  Pan2D: 0
-  rolloffMode: 0
-  BypassEffects: 0
-  BypassListenerEffects: 0
-  BypassReverbZones: 0
-  rolloffCustomCurve:
-    serializedVersion: 2
-    m_Curve:
-    - serializedVersion: 3
-      time: 0
-      value: 1
-      inSlope: 0
-      outSlope: 0
-      tangentMode: 0
-      weightedMode: 0
-      inWeight: 0.33333334
-      outWeight: 0.33333334
-    - serializedVersion: 3
-      time: 1
-      value: 0
-      inSlope: 0
-      outSlope: 0
-      tangentMode: 0
-      weightedMode: 0
-      inWeight: 0.33333334
-      outWeight: 0.33333334
-    m_PreInfinity: 2
-    m_PostInfinity: 2
-    m_RotationOrder: 4
-  panLevelCustomCurve:
-    serializedVersion: 2
-    m_Curve:
-    - serializedVersion: 3
-      time: 0
-      value: 0
-      inSlope: 0
-      outSlope: 0
-      tangentMode: 0
-      weightedMode: 0
-      inWeight: 0.33333334
-      outWeight: 0.33333334
-    m_PreInfinity: 2
-    m_PostInfinity: 2
-    m_RotationOrder: 4
-  spreadCustomCurve:
-    serializedVersion: 2
-    m_Curve:
-    - serializedVersion: 3
-      time: 0
-      value: 0
-      inSlope: 0
-      outSlope: 0
-      tangentMode: 0
-      weightedMode: 0
-      inWeight: 0.33333334
-      outWeight: 0.33333334
-    m_PreInfinity: 2
-    m_PostInfinity: 2
-    m_RotationOrder: 4
-  reverbZoneMixCustomCurve:
-    serializedVersion: 2
-    m_Curve:
-    - serializedVersion: 3
-      time: 0
-      value: 1
-      inSlope: 0
-      outSlope: 0
-      tangentMode: 0
-      weightedMode: 0
-      inWeight: 0.33333334
-      outWeight: 0.33333334
-    m_PreInfinity: 2
-    m_PostInfinity: 2
-    m_RotationOrder: 4
+  _backgroundMusic: {fileID: 2471171845959243506, guid: bc4dd6e772668d64f95ce6ea28022290, type: 3}
 --- !u!1 &3584299649216310804
 GameObject:
   m_ObjectHideFlags: 0