[Verifier][CGP] Allow integer argument to dbg_declare (#134803)
Relaxes the newly added verifier rule to also allow an integer argument
to dbg_declare, which is interpreted as a pointer. Adjust CGP to deal with
it gracefully.
Fixes https://github.com/llvm/llvm-project/issues/134523.
Alternative to https://github.com/llvm/llvm-project/pull/134601.