[video] Fix issues with the event system

[behenate]

Why

Fixes a few issues I encountered with the expo-video event system.

How

• VolumeEvent on android used muted instead of isMuted property name
• Due to double optional the warning VideoPlayer's AVPlayer has been initialized with a AVPlayerItem instead of a VideoPlayerItem was thrown when it wasn't necessary
• The events can be sent before the AppContext is initialised as the video is loaded early. This would lead to warnings. For now the player won't send events when AppContext is not present. In the future we should consider a more robust solution.

Test Plan

Tested in BareExpo on Android 14 emulatore and iOS 17 device.

[expo-bot]

The Pull Request introduced fingerprint changes against the base commit: 9004f96

Fingerprint diff

[
  {
    "type": "dir",
    "filePath": "../../packages/expo-video/android",
    "reasons": [
      "expoAutolinkingAndroid"
    ],
    "hash": "b8302954174022a4fc935c222f9db95f697f9614"
  },
  {
    "type": "dir",
    "filePath": "../../packages/expo-video/ios",
    "reasons": [
      "expoAutolinkingIos"
    ],
    "hash": "621aff951799b82379d5fbe3f95688377b7c8760"
  }
]

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• packages/expo-video/CHANGELOG.md

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