add {parametric,table}_{r,g,b} stages.

add {parametric,table}_{r,g,b} stages.

Think you can take over from here, hook these into SkColorSpaceXform_A2B, and remove the need for fn_1_{r,g,b}?

BUG=skia:664864

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=4888
CQ_INCLUDE_TRYBOTS=master.client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD-Trybot

Change-Id: If573fa2861f32f201f4db28598559290b1eef812
Reviewed-on: https://skia-review.googlesource.com/4888
Commit-Queue: Mike Klein <mtklein@chromium.org>
Reviewed-by: Matt Sarett <msarett@google.com>