Apply video filters in shaders instead of the CPU

[lukexor]

Currently video filters are done in the CPU and consume a few percent of the overall CPU usage during runtime. Moving these to shaders would be faster and open up additional "off the shelf" filtering options

There is a caveat though that this would cause a split in implementation as tetanes-core does not concern itself with shader implementations.

tetanes would instead rely on the ControlDeck::frame_buffer_raw method instead of ControlDeck::frame_buffer in order to provide the shader with the data to process.