feat(benchmarks): Implement the benchmarking system

[christian-pinto]

Description

Implement the benchmarking framework designed in #8.

Sub-issues:

• Implementing the GitHub Runner, deploying it and connecting it to GitHub triggers as per test(benchmark): define benchmark contribution protocol #8
• Extending Nexus Package YAML to allow specifying benchmarks
• Extend Nexus CLI to list benchmarks
• Update Nexus package management so benchmark experiment packages can be added and installed
• Setup ado+ray execution environment (RayCluster)

[michael-johnston]

@christian-pinto We need to capture the above as individual issues and add to roadmap.