always work from fBitmap in table CF

No point holding two copies of our data, an SkBitmap and fStorage array.
The GPU backend wants a bitmap, so make the CPU backend work from that.

Updating the flattened format removed the last use of SkPackBits.

Change-Id: I97f75ebe9324ec5eed37dfe6282e10d0fe08711f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/376599
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Adlai Holler <adlai@google.com>
6 files changed