[includes] Enforce IWYU on SkPath related things

(SkPath itself already is IWYU-enforced)

This will hopefully make it a bit easier to set up a modular
build of Skia that can just export paths without too much
extra stuff.

Change-Id: I915120a3ef6ea7975b2ecc73ee10d269155c730a
Bug: skia:13052, skia:13983
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/617638
Reviewed-by: Herb Derby <herb@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
7 files changed