Rename GrCaps textureSwizzle to readSwizzle.

Change-Id: Ia5e2c4d3ca7346a1ad7559cd158ed632a70145bc
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/260699
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
20 files changed