Bugfixes/Improvements for media player

[kahrendt]

This PR adds some improvements and fixes a lot of outstanding issues with the current media player.

• Bugfix: Disabled the new special-case FIR based resampler due to random crashes
• Bugfix: Audio pipeline correctly reports its state
• Bugfix: FLAC decoding is more robust - it can properly handle running out of data mid-frame
• Bugfix: Fixes some pointer logic with regards to the decoders input buffer - mainly showed up at higher sample rates
• Bugfix: Improves memory handling in resampler - should avoid going past the allocated buffers when converting mono to stereo or upsampling
• Improvement: The DAC mute state is read on boot
• Improvement: Logs what element failed if the pipeline breaks
• Improvement: Fails gracefully if the incoming stream can't be processed (too many channels or incomptable bits per sample)
• Improvement: Configurable output sample rate - useful for experimental 48kHz XMOS firmware
• Improvement: Update TODOs and added a verbose description to nabu_media_player.cpp of how the code is organized and the typical workflow of the media player