Move Painter implementations into Painter

Organize code that will need to be the same into one file.
Have the template implementation confined to the .cpp

Change-Id: I0b256fe538566701c2a72e9f286b373b87f8bdb0
Reviewed-on: https://skia-review.googlesource.com/c/168272
Commit-Queue: Herb Derby <herb@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
3 files changed