GS-hw: Further improve how we handle blend mix 1.

[lightningterror]

Description of Changes

Compensate slightly for Cd*(As + 1) - Cs*As. Try to compensate a bit with substracting 1 (0.00392) * (Alpha + 1) from Cs. The initial factor we chose is 1 (0.00392) as that is the minimum color Cd can be, then we multiply by alpha to get the minimum blended value it can be.

Rationale behind Changes

Improves accuracy slightly, helps MGS3 on Direct3D.

Suggested Testing Steps

Test mgs3 and any other games, logs will trigger if the games use it.

[lightningterror]

Some comparisons, note changes will only be visible on Direct3D since Opengl/Vulkan will use sw blending. Basic blending.

Zombie Hunters: Master:

PR:

OpenGL for reference:

Haunting Ground 2: Master:

PR:

OpenGL for reference:

MGS3: Master:

PR:

OpenGL for reference: