Replace RGB <-> HSL FPs with runtime FPs

Awkwardly, there is still two copies of (some of) this SkSL. We have
helper functions in SkRuntimeEffectPriv.h that implement these
transformations, and those are used by the high contrast color filter.

However: The RGB to HSL code is fairly different, and produces results
that are visibly different. For this CL, I didn't want to impact either
use case, so this is just a migration of the existing .fp code (only
used by HSLA color matrices). We can/should look at merging the
implementation in the future.

Change-Id: I8a9aa6a2d8563ab4333af79a528e406c08b0e1ba
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/419497
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
10 files changed