Allow changing "read framebuffers" at runtime.

Fixes #6149.
Play it a bit safer on rendering mode changes.

This way funny things should be less likely.
Clear jit when changing "fast memory".

This way it takes effect immediately.
Allow jit to be enabled/disabled at runtime.
Report GHA phase shifting.
Merge pull request #6155 from unknownbrackets/ui-tweaks

Allow jit and fast memory to be reconfigured at runtime
Merge pull request #6154 from unknownbrackets/gpu-readpixels

Fix some rendering mode changes
Oops, forgot to move this, darn it.
Oops, reversed the check.
Support memsets of framebuffers as uploads.

Technically should clear stencil too... maybe it'd be better to handle
separately.
Support swizzled framebuffer downloads.

Used in God Eater 2 when showing the load save screen.
Apply unsupported blending modes in the shader.

This handles unsupported fixed color combinations, alpha doubling, etc.
Where possible, tries to avoid it - it means using a blit (without the
framebuffer fetch extension), which can slow things down a lot with tons
of drawcalls.
Double using multiply not add, should be fine.
Skip a few more fixa/fixb combos.
Log when blitting a ton per frame, it can get slow.
Remove outdated comment.

Was all lies.
Oops, typo.
Set a bit to account for fixa/fixb/etc. logic.
Unbind the fbo texture when it's not used.

Just in case there are problems with decimating it or etc.
Ignore the funcs for min/max/absdiff.

Seems from reports that they are indeed ignored, just wanted to verify.