OpenGL: always use texture2d as efb
OpenGL: fix xfb for texture2d
OpenGL: fix efb2tex for texture2d
OpenGL: fix efb2ram for texture2D

This was hacky as hell. Our efb2ram shader generator is just freaked out.
OpenGL: fix emulate format changes for texture2d
OpenGL: drop texture_rect hack

Everything is moved to texture2d (but often in a hacky way), so we don't need this global hack any more.
OpenGL: cleanup efb2tex

Also use attributeless rendering. But we need the src rect, so set it by uniform.
If there is a slowdown here (I doubt as the driver likely has a fast path to update uniforms)
then we should check if this rect changes and only then update the uniform.
OpenGL: attributeless rendering in emulate format changes

only cleanup
OpenGL: attributeless rendering for postprocessing
OpenGL: attributeless rendering for efb2ram

This wasn't as easy as we now have to cache also the uniform locations.
TextureConverter: remove D3D9 foo

This file is in VideoCommon, but as D3D11 doesn't use it and D3D9 is dropped, it's time to clean up.
TextureConverter: Use gl_FragCoord instead of uv0
TextureConverter: Use integer math for swizzling

also move int(efb_coord) -> float(ogl_fb_coord) into WriteSampleColor
Fix for OpenGL ES 3.
TextureConvertion: merge Write*Swizzler
TextureConverter: fix scoping
Fix OpenGL ES 3.
TextureConverter: remove WriteIncrementSampleX
OpenGL: split real xfb + efb2ram framebuffers
OpenGL: reset EFB after efb2ram FB initialization