[clang] Reland "[clang][ssaf][NFC] Move SSAF flags from FrontendOptions to a dedicated SSAFOptions" (PR #205312)

[Balázs Benics via cfe-commits]

steakhal wrote:

I'll merge this without explicit approval as I don't expect a proper review for this MSVC quirk.
I'll monitor for build bot failures.

https://github.com/llvm/llvm-project/pull/205312