RISC-V: Multiple jstz benchmarks script

What

Adds the script src/riscv/scripts/benchmark.sh which runs jstz on riscv and native, for two specified commits.

Usage: benchmark.sh -t <transactions> -i <iterations> -n <native_iterations> -b <base_commit> -c <change_commit>

• -i <iterations> specifies the number of jstz runs when the RISCV interpreter is used.
• -n <native_iterations> specifies the number of jstz runs in natively compiled code.
• -b <base_commit> The commit for the master branch or the 'base'.
• -c <change_commit> The commit for the tested change.

To view the full results, run logs are saved in files named <BASE/CHANGE>_<NATIVE/RISCV>_<commit>.run.

Tip: Commits can also be branch names!

Why

Easier to get benchmark timings, on both the local machine and the remote machine.

How

Adds the script src/riscv/scripts/benchmark.sh with appropiate options.

Manually Testing

make -C src/riscv all
./scripts -t 1 -i 3 -b branch_A -c branch_B

Where branch_A & branch_B are branches on top of this change.

Benchmarking

Performance not impacted

	master	This MR	Improvement
$MyMachine	X.XXX TPS (1/XXX native)	X.XXX TPS (1/XXX native)	XX.XX%
Benchmark Machine	Y.YYY TPS (1/YYY native)	Y.YYY TPS (1/YYY native)	YY.YY%

Tasks for the Author

• Link all Linear issues related to this MR using magic words (e.g. part of, relates to, closes).
• Eliminate dead code and other spurious artefacts introduced in your changes.
• Document new public functions, methods and types.
• Make sure the documentation for updated functions, methods, and types is correct.
• Add tests for bugs that have been fixed.
• Put in reasonable effort to ensure that CI will pass.
• Benchmark performance and populate the table above if needed.
• Write commit messages to reflect the changes they're about.
• Self-review your changes to ensure they are high-quality.
• Complete all of the above before assigning this MR to reviewers.