[clang-cl] Add parsing support for a bunch of new flags

MSVC has added some new flags. Although they're not supported, this adds
parsing support for them so clang-cl doesn't treat them as filenames.

Except for /fsanitize=address which we do support. (clang-cl already
exposes the -fsanitize= option, but this allows using the
MSVC-spelling with a slash.)

Differential revision: https://reviews.llvm.org/D101439