Fixes Jak 1 shadow color. Old behavior is subtractive blend with a hardcoded value, which often times look way too dark, but it looks like the actual game uses some sort of multiplicative blend and a customizable shadow color (for all shadows at once). Before vs after:     Also fixes #2646
This PR is a combination of https://github.com/open-goal/jak-project/pull/2507 and some additional changes to port Shadow VU1 to OpenGL. As far as I can tell, it's working. --------- Co-authored-by: Hat Kid <6624576+Hat-Kid@users.noreply.github.com>