Add uniforms to SkRP debug trace data.

When writing a debug trace, we now allocate a scratch value slot for
each uniform and copy the uniform values into the scratch slots at
the start of execution. This naturally causes them to appear in the
debug trace.

Change-Id: Icc43e42cbdf34476eb8317866601d0eb240d2413
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/664338
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
8 files changed