In equivalence with `LLVMFunctionMixin`, add a mixin that allows
writing a pipe that instead of defining the `runOnFunction` method it
defines the `runOnCliftFunction` which receives both the
`module::Function` and the `FunctionOp`.
Add a mixin class for piperuns that work on an LLVM module and need
both the model function and the `llvm::Function`. Pipe that inherit this
mixin will receive both the model and LLVM function in the
`runOnLLVMFunction` method.
Lauri Vasama