[graphite] Flesh out Device/SDC a bit more

Renames SDCTask -> RenderPassTask and adds comments describing its
purpose. Has SDC use a DrawList and expose similar drawing functions.
Stubs out all Device methods that will eventually need to be supported,
but groups them into in-scope and out-of-scope sections. Implements the
drawing functions in terms of drawPath() and has drawPath() invoke the
SDC functions (with untested support for path effects, hairline, etc.).

Bug: skia:12466
Change-Id: Id661fc987aeb35f0dfa536c0cb0b6210742cf32c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/452233
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
10 files changed