freedreno/ir3: disasm + parser updates and testing

Pulls out a few of the disasm fixes, additional disasm test vectors, plus @cwabbott0's movmsk support, from !7997 (merged), and wires up assembler testing.

The idea is that before I start implementing xml based instruction encoding in !7997 (merged) I want a way to be able to test it. I might have crawled down a parser rabbit hole. (OTOH a more complete parser makes things like computerator more useful.)