[fontations-backend] Resolve palette overrides and store CPAL palette

Use the newly introduced resolve_palette() FFI functionality to
resolve user-specified palette overrides and store the resulting
resolved palette in the Fontations SkTypeface backend.

resolve_palette() functionality tested in [1].

[1] https://skia-review.googlesource.com/c/skia/+/792856/1/src/ports/fontations/src/ffi.rs#545

Bug: b/301562314
Change-Id: Ie4f9bf1777e429c6d45fc2898c816de1c8dea50b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/795596
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
Auto-Submit: Dominik Röttsches <drott@chromium.org>
2 files changed