[mlir][EmitC] Add `verbatim` op (#79584)

The `verbatim` operation produces no results and the value is emitted as
is followed by a line break ('\n' character) during translation.

Note: Use with caution. This operation can have arbitrary effects on the
semantics of the emitted code. Use semantically more meaningful
operations whenever possible. Additionally this op is *NOT* intended to
be used to inject large snippets of code.

This operation can be used in situations where a more suitable operation
is not yet implemented in the dialect or where preprocessor directives
interfere with the structure of the code.

Co-authored-by: Marius Brehler <marius.brehler@iml.fraunhofer.de>