Add initial implementation of GrShape and GrStyle classes and tests

The initial intent is to use GrShape to simplify the mask blur code paths. However, I also want to use this to explore a more unified drawing code flow for different geometry types. The goal is to have a single representation for geometries+styling that attempts to always keep the geometry in the simplest form (e.g. preferring rrects to paths). It also allows for converting styling information into modified geometry and for computing consistent keys.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1822723003

Committed: https://skia.googlesource.com/skia/+/c885dacfe4625af8b0e2e5c6e8a8ae8dc2d620a8

Review URL: https://codereview.chromium.org/1822723003
6 files changed