Load and use user-distruted certificates in TrustStoreWin.

https://docs.microsoft.com/en-us/dotnet/api/system.security.cryptography.x509certificates.storename?view=net-5.0
documents the distrusted certificate settings, which for some reason is
more up to date than
https://docs.microsoft.com/en-us/windows/win32/seccrypto/system-store-locations

Bug: 1239258
Change-Id: Ie2fe9476ed6828942bc3f63256446bfa46c5ef80
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3143874


Commit-Queue: Hubert Chao <hchao@chromium.org>
Reviewed-by: Ryan Sleevi <rsleevi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#919276}