Re-introduce tablegen constraint for "is-this-a-CIR-type" and use it here

[bcardosolopes]

          Since this is basically all types, we could probably get this from tablegen. @sitio-couto recently removed a tablegen constraint for checking that would have been helpful there. Let me get an issue for this.

Originally posted by @bcardosolopes in https://github.com/llvm/clangir/pull/333#discussion_r1402658928