GS/HW: Optimize sw/hdr colclip on some blend formulas.

[lightningterror]

Description of Changes

GS/HW: Optimize sw/hdr colclip on some blend formulas.
Alpha is either As or Af.
Cd*Alpha, Cd*(1 - Alpha).
When Alpha <= 128 we can let hw blend do it's thing as it won't be able to wrap.

Rationale behind Changes

Brrr, less draw calls, copies, barriers.

Suggested Testing Steps

Helps Sly 2, Big Mutha Truckers, Lord of the rings Third age, so test these games.

Big Mutha Truckers_SLUS-20291_20230214212340 ['Barriers: -2 [39=>37]']
Big.Mutha.Truckers ['Barriers: -2 [134=>132]']
Lord of the Rings, The - The Third Age_SLES-52801_20230919222807 ['Draw Calls: -2 [44=>42]', 'Render Passes: -1 [16=>15]', 'Copies: -1 [8=>7]']
Lord_of_the_Rings_The_-_The_Third_Age_SLES-52801_20230707223226 ['Draw Calls: -2 [189=>187]', 'Copies: -2 [8=>6]']
Lord_of_the_Rings_The_-_The_Third_Age_SLUS-21027_20230404183506 ['Draw Calls: -2 [150=>148]', 'Render Passes: -1 [16=>15]', 'Copies: -2 [9=>7]']
Signore degli Anelli, Il - La Terza Era_SLES-52804_20230331154537 ['Draw Calls: -2 [125=>123]', 'Render Passes: -1 [16=>15]', 'Copies: -2 [9=>7]']

[refractionpcsx2]

kind of an aside but would be nice for clarity in this PR, can you update the variable names of alpha_less_one, alpha_c0_less_max_one, alpha_c2_less_one maybe make them less_eq_ or something, because they check <= not just <

Further to that, couldn't Ad of <= 128 also pass if there's no overlap or alpha is masked (or As is <= 128 also, I guess)?

You could also maybe omit the blend_a == 2, since as long as the subtraction is the destination colour, it shouldn't increase the intensity.

[lightningterror]

or alpha is masked

That's already handled as CdAs, Cd(1 - As) since the formula is changed it's picked up.
Edit: actually it isn't picked up but it can be.
For RTADescale it can be handled, just wanted to leave it out for another time.

[lightningterror]

So I checked if it's worth adding Ad conditions but nothing uses them so not going to add them.
Get alpha values have been renamed as suggested.

[oltolm]

You forgot to rename a variable pxAssert(m_conf.ps.blend_d == 2 || alpha_one);

[lightningterror]

Seems so, I'll fix it.