[asan][test][win] Move MSVC-specific tests into a subdir

This moves all but one remaining tests which use clang-cl and test
MSVC-specific behaviour into its own subdirectory. `dll_host.cpp` test
is excluded from the move because other tests also depend on its source
file, making it not MSVC-specific.

Differential Revision: https://reviews.llvm.org/D150271