Move WIP license reporting here from core?

[bollwyvl]

Over on jupyterlab/jupyterlab#9779 I've started some work to make frontend library license reporting more structured. The current alpha release includes a third-party-licenses.txt, but the baseline report is pretty simple. That PR moves the reporting to a predictable third-party-license.json structure (even have a schema, but got rid of it) generated by a single codepath in @jupyterlab/builder, and on top of it builds:

• an API endpoint /lab/api/licenses
• a CLI tool jupyter lab licenses

...with all the fixin's: different output formats, etc.

Those things would be fine to land there, exclusively, but license compliance seems a thing that is probably even more important to downstream Lab-derived applications. Also, the federated_modules data definitions live over here, which is a pretty important piece.

If this happened, that PR would probably split into:

• jupyterlab/jupyterlab
  • @jupyterlab/builder dev tool which generates third-party-licenses.json
  • @jupyterlab/licenses-extension which consumes the API
• jupyterlab/jupyterlab_server
  • the LicensesManager and LicensesHandler
• not sure
  • the LabLicensesApp for the CLI
    • might be nice to have here for folks to subclass

Any thoughts appreciated!

[afshin]

Adding the server endpoints seems sound to me, the rest follows 👍

[bollwyvl]

Dig. Will get on that this evening.

[bollwyvl]

Didn't make it to this (but did get lab 3.0.8 out the door on conda-forge, with some corrected pins and more CLI checks 😪 )

[bollwyvl]

Aight, started the PR (#161) and the plumbing to manage the co-development of the features. This is gonna take a sec...