Added functionality to `Choose preset input` button. The picker allows the user to select a preset input from a list of loaded preset playlists. The selected preset input is then used to populate the ExoPlayer with the corresponding media items.
PiperOrigin-RevId: 704626144
The JSON file contains a list of playlists, each with a name and a list of media items. The EffectActivity loads the JSON file and creates a list of PlaylistHolder objects, which contain the playlist name and the list of media items.
PiperOrigin-RevId: 703069411
Added the functionality for `Choose local file` button to be able to go and select a local file from the device. The file was then displayed by using ExoPlayer inside PlayerView.
PiperOrigin-RevId: 693756565
Added a basic UI to the effect demo app, including a PlayerView, buttons to choose preset input and choose local file, and a button to apply effects. The buttons are currently not implemented, and the app will show a snackbar message when they are clicked.
PiperOrigin-RevId: 693751272
