[bazel] Break up shaper srcs

Change-Id: I7ab02740e285b45522816a785d353cbd9602ae3f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/628116
Reviewed-by: Ben Wagner <bungeman@google.com>
Auto-Submit: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
3 files changed