Move references to BitmapDevice into separate file

This makes it easier to remove the new file and ensure that
SkCanvas does not reference SkBitmapDevice.

Bug: skia:14192
Change-Id: Iad8ffa4e900076af2e81b567afbffc019cd4bbab
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/658299
Reviewed-by: Florin Malita <fmalita@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
5 files changed