Add a "conservative raster" flag to GrPipeline and implement in Vulkan

This flag is not yet used or tested. Both will come next when we
enable mixed sampled ccpr.

Change-Id: Ic242010b1f0b8d81b83731960283e4231f301fd1
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/252258
Commit-Queue: Chris Dalton <csmartdalton@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
10 files changed