[Feature Request] add black & white "color fitler" shaders to the default shaders

[checktext00]

add black & white "color filter" style shaders to emulate black & white CRT TVs to the default shaders, it could be under a "Color Filters" folder and used by appending the B&W shader on top of an existing CRT shader (or any other shader)

I found some on the libretro forums, but they are 10 year old GLSL shaders that don't work in RetroArch anymore: https://forums.libretro.com/t/black-white-shaders-classic-sdtv-hdtv/1606