[GlobalISel][InlineAsm] Add support for basic output operand constraints

Reviewers: arsenm, dsanders, aemerson, volkan, t.p.northover, paquette

Reviewed By: arsenm

Subscribers: gargaroff, wdng, rovka, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D78318