[trace] Scaffold "thread trace dump instructions"
Depends on D88841
As per the discussion in the RFC, we'll implement both
thread trace dump [instructions | functions]
This is the first step in implementing the "instructions" dumping command.
- A minimal ProcessTrace plugin for representing processes from a trace file. I noticed that it was a required step to mimic how core-based processes are initialized, e.g. ProcessElfCore and ProcessMinidump. I haven't had the need to create ThreadTrace yet, though. So far HistoryThread seems good enough.
- The command handling itself in CommandObjectThread, which outputs a placeholder text instead of the actual instructions. I'll do that part in the next diff.
Differential Revision: https://reviews.llvm.org/D88769