docs: Add debugging instructions for MacOS runner connections and nesting
This MR adds to the MacOS runner documentation:
- Adding a convenience link to the GCP console list of MacOS shard runner managers for accessing runner managers
- Creating a troubleshooting section for debugging connections between runner managers and host Macs
- Documenting commands for managing nested VMs with the nesting client
- Adding information about log locations and common nesting service issues
Edited by Davis Bickford