feat: add/update benchmark of loss prevention pipelines documentation and make targets

[jim-wang-intel]

PR Checklist

• [x] Added label to the Pull Request for easier discoverability and search
• [x] Commit Message meets guidelines as indicated in the URL https://github.com/intel-retail/loss-prevention/blob/main/CONTRIBUTING.md
• [x] Every commit is a single defect fix and does not mix feature addition or changes
• [ ] Unit Tests have been added for new changes
• [x] Updated Documentation as relevant to the changes
• [ ] All commented code has been removed
• [ ] If you've added a dependency, you've ensured license is compatible with repository license and clearly outlined the added dependency.
• [ ] PR change contains code related to security
• [ ] PR introduces changes that breaks compatibility with other modules (If YES, please provide details below)

What are you changing?

• add benchmark documentation
• update make targets: benchmark, benchmark-stream-density to have the right parameters for running result outputs
• add make target: clean-benchmark-results to be easier for cleaning between new sets of benchmarks

Issue this PR will close

close: #15

Anything the reviewer should know when reviewing this PR?

Test Instructions if applicable

• git clone this PR
• follow the instructions documented in benchmark.md
• you should be able to run the benchmark and see the results for both number of pipelines and stream density for loss prevention

If the there are associated PRs in other repositories, please link them here (i.e. intel-retail/loss-prevention )

[jim-wang-intel]

On my run, I had to specify python3 in the make targets and in the benchmark-scripts target init-packages I had to force the packages to install with --break-system-packages since I am not using a venv...

Thanks @seanohair22 for letting us know: the existing documentation suggests we use vent in Prerequisite section; but that is a good testing for non-virtual env. Usually I would also suggest running in venv so that if somehow python is messed up, you are less miserable :-) .