A few bug fixes for SkOverdrawCanvas

(1) Use SkNWayCanvas to pass through non-draw canvas calls.
(2) Do not count overdraw on the initial canvas clear.
(3) Avoid counting overdraw for transparent lattice regions.
(4) Respect some properties of input paint.

BUG:32370375

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=5150

Change-Id: I8fe6b9df7247d637c710628aefdfee82a61048c2
Reviewed-on: https://skia-review.googlesource.com/5150
Commit-Queue: Matt Sarett <msarett@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
2 files changed