[mlir] Fix the names of exported functions

The names of the functions that are supposed to be exported do not match the implementations. This is due in part to https://github.com/llvm/llvm-project/commit/cac7aabbd8236bef2909bfc0dbba17644f7aaade.

This change makes the implementations and declarations match and adds a couple missing declarations.

The new names follow the pattern of the existing `verify` functions where the prefix is maintained as `_mlir_ciface_` but the suffix follows the new naming convention.

Reviewed By: rriddle

Differential Revision: https://reviews.llvm.org/D124891