[clang] Reland "[clang][ssaf][NFC] Move SSAF flags from FrontendOptions to a dedicated SSAFOptions" (PR #204798)

[Balázs Benics via cfe-commits]

steakhal wrote:

Moved the SSAFOptions.h to the clangFrontend library in 8132a5ff16d71eec68020cc6e76150596b643dfc - similar to what the other options headers to, for example: `MigratorOptions.h`

This should solve the layering violation reported in https://github.com/llvm/llvm-project/pull/204621#issuecomment-4746536754 @rupprecht Could you please confirm that this way it would work?

https://github.com/llvm/llvm-project/pull/204798