[piet] Add piet-gpu support code
- Added a third-party DEPS entry for piet-gpu.
- Added a build script and instructions to compile the
piet-gpu/pgpu-render Rust crate manually.
- Added GN targets to pull in library include and dylib dependencies,
conditioned on a new `skia_use_piet` GN arg.
- Added C++ support code for the piet library under src/gpu/piet
- Made piet a conditional dependency of graphite.
Bug: b/241580255
Change-Id: I666195e93bb1f43cf07d918a23199075b479f1a1
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/566017
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Arman Uguray <armansito@google.com>
12 files changed
