refactor freetype common into utils

No need to make these utilities be part of the class hierarchy.
Also, rename files to reflect this.

Change-Id: If3e742f71170771e64c258591d19be2896c0b73d
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/806778
Reviewed-by: Florin Malita <fmalita@google.com>
Auto-Submit: Mike Reed <mike@reedtribe.org>
Commit-Queue: Florin Malita <fmalita@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
3 files changed