Fix regression on Fire Emblem: Three Houses when using native fp16.

Workaround potential bug on Nvidia's driver where only updating high
attributes leaves low attributes out dated.

account for the fact that program.*memory_size is in units of bytes.

Used by MH:Rise

Fixes OpenGL.

GLASM is getting good enough that we can move it out of advanced
graphics settings. This removes the setting `use_assembly_shaders`,
opting for a enum class `shader_backend`. This comes with the benefits
that it is extensible for additional shader backends besides GLSL and
GLASM, and this will work better with a QComboBox.

Qt removes the related assembly shader setting from the Advanced
Graphics section and places it as a new QComboBox in the API Settings
group. This will replace the Vulkan device selector when OpenGL is
selected.

Additionally, mark all of the custom anisotropic filtering settings as
"WILL BREAK THINGS", as that is the case with a select few games.

Put all varyings into a single std::bitset with helpers to access it.

Implement passthrough geometry shaders using host's.

Useful for mobile and Intel Xe devices.

This ensures the original operand values are not overwritten when being used in the overflow detection.