Add CLI usage

[non25]

Hey! 🙂
Not even a month has passed. 😁

I'm not super happy about exec polluting config.ts to skip console.log's, but I'm not sure whether it is a good idea to overhaul more for such simple addition. 🤔

Also not super happy about having to have a compatibility adapter for startServer, but I've ran out of ideas for now, maybe tomorrow I'll have better ones. 😁
Just wanted to avoid using process.argv directly and rely on yargs entirely. 🤔

Let me know if it makes sense to add example of using -e to README.md, or in --help for users that are not aware of output piping like figma-server-mcp -e "figma-link" > figma-node.yaml.
I tried to avoid adding more arguments like --output. 🙂

Also figma links could contain & which would run whatever after & as a "command", so suggesting quoting figma link probably makes sense as well. 🤔

Also out of scope, but I checked out if there's some solution to the process.argv with type inference and it appears there is one. 🤔
https://bloomberg.github.io/stricli/docs/getting-started/alternatives

Feel free to do anything with the PR.
Let me know your thoughts 🙂
Thanks.

[non25]

@GLips any thoughts? 🙂