MediaChannelConfiguration クラスは使用されていないので削除する

[zztkm]

変更内容

• [CHANGE] MediaChannelConfiguration クラスを削除する
  • MediaChannelConfiguration.swift には MediaChannelConfiguration クラスしかないのでファイルごと削除

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This pull request includes significant changes to the Sora project, primarily focusing on the removal of the MediaChannelConfiguration class and updating the WebRTC version. Below is a summary of the most important changes:

Removal of MediaChannelConfiguration Class

• Sora/MediaChannelConfiguration.swift: Deleted the entire file as it only contained the MediaChannelConfiguration class, which has been removed.

Documentation Updates

• CHANGES.md: Documented the removal of the MediaChannelConfiguration class and updated the WebRTC version to m127.6533.1.1.