Add CHAD and WTPT functions to public API

Change-Id: I1ea6b234ae63fa5546d283027a62960051f7b4a1
Reviewed-on: https://skia-review.googlesource.com/c/skcms/+/253916
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
56 files changed