Generate NM config

[atanasdinov]

• Initializes the nmc Rust crate
  • nmc will be a CLI exposing generate and apply subcommands
  • generate will generate the network configuration for a set of different hosts defined as YAML files in a user provided directory
  • apply will identify the host which the CLI is running on and apply the network configuration (replacing the existing Go implementation)
• Adds initial generate implementation
• Follow ups will include further validation, more tests, CI changes, documentation

[diconico07]

Mostly nits, LGTM