Generalize dispatcher for all job types

[cosenal]

Description

Generalizing the job dispatcher so that we don't need to create one for each job type.
Code specific to a job type should be created in the handlers.

Note: I will do the same for polling, but in a separate PR to make the PRs easier to digest.

Issue ticket number and link

Fixes #65

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Unit tests, plus smoke tested with

python metriq_gym/dispatch_job.py metriq_gym/schemas/examples/quantum_volume.example.json

Checklist:

• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules (or not applicable)

[vprusso]

Instead of three separate imports from the same place, can we just have one that imports all three?

Suggested change

	from metriq_gym.benchmarks.benchmark import Benchmark
	from metriq_gym.benchmarks.benchmark import (
	Benchmark,
	CLOPS,
	QuantumVolume,
	)

[cosenal]

Right now they are coming from three different modules, not from the same place. To achieve what you are suggesting, we would need to export them using __init__.py files, which I find it becomes unmanageable after a while.

[vprusso]

Do we need this in a main block? Can we take this out like so:

Suggested change

	def main():
	load_dotenv()
	args = parse_arguments()
	params = load_and_validate(args.input_file)
	job_manager = JobManager(args.jobs_file)
	HANDLERS[JobType(params["benchmark_name"])](args, params, job_manager).dispatch_handler()

[cosenal]

I like to wrap it inside if __name__ == "__main__": so it's clear that it's a script meant to be run directly and not imported from other modules.
Note that this is going away as well at some point, and we will have only one cli script with a cli manager handling all the cli commands (Issue #56)

[vprusso]

Can we make this an abstract class? This would be a nice way to enforce that any subsequent benchmarks we implement have the dispatch and poll handlers.

[cosenal]

Do you mean a formal interface defined using abc.ABCMeta? It feels a bit over-engineering at the moment, given how small the codebase is. Also, until we migrate poll methods too, I wouldn't enforce the handler definition to be too strict.