Added a local identity provider.

[3coins]

Partially fixes #1181, long term we might want to make an update to jupyter-server for local installations.

This PR adds a local identity provider to switch user identity to local host credentials. The identity provider is only appropriate for local installations of Jupyter.

jupyter lab --ServerApp.identity_provider_class=jupyter_ai.auth.identity.LocalIdentityProvider

Before	After

Note: Excluding the change to jupyter_ai.json, as I wasn't able to get this working, even though it is being copied to a directory in jupyter --paths.

(jupyter-ai) pijain@bcd07462b5c2 jupyter-ai % jupyter --paths
config:
    /Users/pijain/.jupyter
    /Users/pijain/.local/etc/jupyter
    /Users/pijain/miniforge3/envs/jupyter-ai/etc/jupyter
    /usr/local/etc/jupyter
    /etc/jupyter
data:
    /Users/pijain/Library/Jupyter
    /Users/pijain/.local/share/jupyter
    /Users/pijain/miniforge3/envs/jupyter-ai/share/jupyter
    /usr/local/share/jupyter
    /usr/share/jupyter
runtime:
    /Users/pijain/Library/Jupyter/runtime

(jupyter-ai) pijain@bcd07462b5c2 jupyter-ai % cat /Users/pijain/miniforge3/envs/jupyter-ai/etc/jupyter/jupyter_server_config.d/jupyter_ai.json
{
  "ServerApp": {
    "jpserver_extensions": {
      "jupyter_ai": true
    },
    "identity_provider_class": "jupyter_ai.auth.identity.LocalIdentityProvider"
  }
}%  

[srdas]

Looks good. I tested it and it works, even without the --no-browser option.

Happy to approve once you are done with changes.

[srdas]

LGTM! Thanks for closing this out!

[JGuinegagne]

how long can username be?

if it's bounded it's fine, but line 13 is a loop within a loop so if username is large it could be expensive.
The variable name suggests it should be a small string in which case it's not really an issue.

Otherwise, one simple way to do it is to interrupt the loop on line 13 as soon as two consonants were found.

[JGuinegagne]

nit: not sure we care, but generally python docstring end w/ a period .

[JGuinegagne]

nit: not using variable e, interesting that the linter isn't picking this up...

[JGuinegagne]

nit: variable redefinition, perhaps it's okay but just flagging it.

Also, why are we awaiting here? get_user is not async as far as I can tell.