[mlir-tblgen] Support binding multi-results of NativeCodeCall

We are able to bind NativeCodeCall result as binding operation. To make
table-gen have better understanding in the form of helper function,
we need to specify the number of return values in the NativeCodeCall
template. A VoidNativeCodeCall is added for void case.

Reviewed By: jpienaar

Differential Revision: https://reviews.llvm.org/D102160