Remove large swaths of code related to .fp files

Change-Id: Id2061ebe7873aa8b9480a2d8b0133c2fb79e79bb
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/424098
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
62 files changed