[clang] [Clang][ssaf] Add missing instantiations of `Registry<JSONFormat::FormatInfo>` (PR #181806)

[Balázs Benics via cfe-commits]

steakhal wrote:

Unless you oppose, I'd want to create only one fixup commit. That would contain this fix, and also the fix for gcc-7.5 which is of different nature.

https://github.com/llvm/llvm-project/pull/181806