Add no-MSE build option

[TheModMaker]

trafficstars

After #89, we'll support playing HLS content without using MSE. If apps are only going to play HLS content, we could greatly reduce the size of the binary by removing most of the media pipeline. We could remove the JavaScript MSE types, the custom media tracking, default demuxers/decoders/renderers, and all of FFmpeg and SDL. In this mode, we would only support playing HLS content through native AVPlayer.