Add support for sqrt() to RP codegen.

The sqrt() intrinsic test was previously non-functional, although
it was mostly usable. It's now been been updated to run as part of
our standard dm test suite.

Change-Id: I0dd5f9db6898375f778096d2eb32b62743fdabc9
Bug: skia:13676
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/632037
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
8 files changed