[tsp-client] Add a metadata file when generating a client library

[catalinaperalta]

We need a metadata file to track the dependencies that were used at the time of generating a client library. It should include information about the packages specified in the emitter-package.json (and lock file?). Additionally, it would be good to have data on the tsp-client version that was used to generate.

[catalinaperalta]

Also add a warning if the spec repo's compiler version is ahead of the emitter's compiler version and warn that this could cause failures.

[catalinaperalta]

Goals:

• Warn the tsp-client user that the mismatch may create errors
• Save a metadata file on successful generation, that contains at the very least the emitter-package.json that was used

Cherry on top for later:

• Add a way to re-consume the metadata to rebuild the same thing (bypass emitter-package,json and used saved information instead)