Cleanup legacy audio engine's audio context in dispose() (#16412)

Author: docEdub

packages/dev/core/src/Audio/audioEngine.ts

@@ -335,6 +335,9 @@ export class AudioEngine implements IAudioEngine {
 
         this.onAudioUnlockedObservable.clear();
         this.onAudioLockedObservable.clear();
+
+        this._audioContext?.close();
+        this._audioContext = null;
     }
 
     /**

packages/dev/core/test/unit/Audio/helpers/mockedAudioObjects.ts

@@ -100,6 +100,10 @@ export class MockedAudioObjects {
             return {
                 currentTime: 0,
                 state: "running",
+                close: jest.fn().mockName("close").mockImplementation(() => {
+                    this.audioContext.state = "closed";
+                    return Promise.resolve();
+                }),
                 createBufferSource: jest.fn().mockName("createBufferSource").mockImplementation(() => {
                     const bufferSource = new AudioBufferSourceNodeMock;
                     this._audioBufferSources.push(bufferSource);