Add the ability to disable the LCD shader on the GB cores (GB, GBC, GBA)

[synesthesium]

Is your feature request related to a problem? Please describe.

The problem in my case is that when running on lower resolution screens (1600x720 in my case) in portrait mode, the edges of the filter are not very well defined, and it follows that it looks much more like a bilinear filtering is taking place than an LCD filter (ew.)
Also, some people may just prefer it without that.

Describe the solution you'd like

Similarly to the LCD Ghosting option, I would like there to be an option to just disable the LCD shader entirely. I'm not really sure why it's there by default, and especially why it's not disablable at all.

Describe alternatives you've considered

Long term, it would be cool to have some sort of GLSL shader selection option like RetroArch does in my opinion. Short term though, I'm just asking for a simple option to disable this shader.

Additional context

Here's the shader in portrait mode. Notice how muddy the image looks.

Here's the same shader in landscape mode.

[synesthesium]

i may be stupid