[FEA]: Add `.verify` tests for `<cuda/std/format>`

[davebayer]

Currently, we only test the well-formed format strings. We should add .verify tests for invalid strings and make sure they fail the compilation.

[Darshan-Baslani]

Hi! I'd love to take this on as my first contribution.

[davebayer]

Hi! I can assign you to the issue, however it's not trivial because the .verify tests basically currently don't work with our infrastructure. Since we support multiple compilers, we'd like to just check that a some diagnostic is emitted on a given line. We probably can't check the exact error messages. Let us know if you need any help :)