Add a new darwin build stage to OpenSearch distribution pipeline

[prudhvigodithi]

Is your feature request related to a problem? Please describe

Part of: #2216
Add a new darwin build stage to OpenSearch distribution pipeline.

Describe the solution you'd like

The new stage, part of pipeline will be restricted to run on MacOS agents, so the platform can be inferred as darwin, with the existing build_workflow and assemble_workflow logic the ouput should be tar artifcat for darwin.

Describe alternatives you've considered

N/A

Additional context

N/A

[prudhvigodithi]

Closing this issue as the associated PR #2362 is merged.
Thank you