[rlsw] Simplify framebuffer logic and add blit/copy fast path (#5312)

* consistency tweak

* unified color and depth buffer

* tweaks

* review the storage of clear values + complete get/set depth value

* copy/blit fast path

* better simd read/write

* framebuffer alignment

* fix 'typo'
my french slipped out

Author: Bigfoot71