Reland "unorm/unorm -> to_unorm/from_unorm"

This is a reland of cd4e5662aca3097ee3b19633df1c0ea708342223

Original change's description:
> unorm/unorm -> to_unorm/from_unorm
> 
> Just better names, no real change.
> 
> Change-Id: I7a67ccb49d5367137b6a1f100434cb866f15ea71
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/268389
> Auto-Submit: Mike Klein <mtklein@google.com>
> Reviewed-by: Herb Derby <herb@google.com>
> Commit-Queue: Mike Klein <mtklein@google.com>

Change-Id: I2843cf77a4b3c8888ef835b2ad5045d900d44e3a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/268516
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
4 files changed