Rename SkStrikeSpecStorage -> SkStrikeSpec

SkStrikeSpecStorage was a temporary name until all uses of
SkStrikeSpec were cleaned up. Do the final rename.

Change-Id: Iaba987ecdfe46ca9eee8d530d5095840cdca300d
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/219209
Reviewed-by: Herb Derby <herb@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Herb Derby <herb@google.com>
18 files changed