Add support for ShaderCapsFactory to skslc.

In a followup CL, this will allow SkSL golden tests to control their
caps settings.

Change-Id: I2aace30e5567de8a52690c89b27bbab0c2d766e3
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/317177
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
4 files changed