Integration into gem5

[uslsteen]

Integrate into gem5 workflow uScope Tool usage.

1. One possible use case is collecting JSON traces directly at runtime:

1.1 Collect pipeline events:

./build/RISCV/gem5.opt --debug-flags=PipePerfetto --debug-file=<path_to_trace.json> <config_script> [config_script_options] --cmd=<program_path> [other_gem5_options]

1.2. Collect only FU execution events:

./build/RISCV/gem5.opt --debug-flags=ExecPerfetto --debug-file=<path_to_trace.json> <config_script> [config_script_options] --cmd=<program_path> [other_gem5_options]

1.3. Collect both:

./build/RISCV/gem5.opt --debug-flags=PipeViewPerfetto --debug-file=<path_to_trace.json> <config_script> [config_script_options] --cmd=<program_path> [other_gem5_options]

Exact naming of --debug-flags is TBD.