[globalisel][tablegen] Added instruction emission to the state-machine-based matcher.

Summary:
This further improves the compile-time regressions that will be caused by a
re-commit of r303259.

Also added included preliminary work in preparation for the multi-insn emitter
since I needed to change the relevant part of the API for this patch anyway.

Depends on D33758

Reviewers: rovka, vitalybuka, ab, t.p.northover, qcolombet, aditya_nandakumar

Reviewed By: ab

Subscribers: kristof.beyls, igorb, llvm-commits

Differential Revision: https://reviews.llvm.org/D33764

llvm-svn: 307133