We were using a static SystemInfo in two places. Consolidate the
SystemInfo collection to a single location. Also renames Nvidia to
NVIDIA to be consistent with the company naming. And adds a few helpers
to SystemInfo for GPU detection.

Will lead to test changes to reduce flakiness on Intel Windows.

Bug: angleproject:3261
Change-Id: I4e0addf19d6fe26b4d31a1289efce72092a0a1dd
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1531533Reviewed-by: Jonah Ryan-Davis <jonahr@google.com>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>