Create subdirs for test data

tests/data/activity/activity.json

tests/data/albums/album.json

tests/data/albums/paginated_album_list.json

tests/data/artists/artist_with_albums.json

tests/data/artists/paginated_artist_with_albums_list.json

tests/data/artists/simple_artist.json

tests/data/attachments/attachment.json

tests/data/auth/subsonic.json

tests/data/auth/user_details.json

tests/data/auth/user_me.json

tests/data/auth/verify_email.json

tests/data/auth/verify_email_request.json

tests/data/channels/channel.json

tests/data/channels/paginated_channel_list.json

tests/data/common/api_mutation.json

tests/data/common/paginated_api_mutation_list.json

tests/data/favorites/favorites_all.json

tests/data/favorites/paginated_user_track_favorite_list.json

tests/data/favorites/track_favorite_write.json

tests/data/favorites/track_favorite_write_request.json