[gn build] Add support for check-asan

With these changes, check-asan passes on Linux and Windows.

There are a couple libraries we need to add support for, asan_static, asan_preinit, and the shared library version of asan proper.
Since we need to build the asan proper sources twice, once with -DASAN_DYNAMIC and once without, those sources are no longer in a source_set.
Much of the check-asan target is taken from the existing check-hwasan target.

Reviewed By: thakis

Differential Revision: https://reviews.llvm.org/D118307