MPVActivity: clean up copyAssets
MPVActivity: clean up copyAssets

mpv-android/mpv-android,jeeb/mpv-android,jeeb/mpv-android,mpv-android/mpv-android,jeeb/mpv-android,mpv-android/mpv-android,jeeb/mpv-android,mpv-android/mpv-android,jeeb/mpv-android,mpv-android/mpv-android