Play music continued when open app

[Yamagn]

Description

iOSではAVAudioSessionCategoryの設定がPlayandRecordになっていたためアプリを開いた段階で別アプリで再生中の音楽の再生が停止してしまっていた。 そこで通常の設定をAmbientに変更し、Playbackに変更するメソッドを追加した。

Related Issue

Motivation and Context

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [ ] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [ ] I have read the CONTRIBUTING document.