[mlir][LLVM] Add support for operand_attrs to InlineAsmOp

This revision adds enough support to allow InlineAsmOp to work properly with indirect memory constraints "*m".
These require an explicit "elementtype" TypeAttr on the operands to pass LLVM verification and need to be provided.

Reviewed By: bkramer

Differential Revision: https://reviews.llvm.org/D118006