Change from jupyter_server to jupyterlite-core jupyterlab

[mcbarton]

Description

Please include a summary of changes, motivation and context for this PR.

A better alternative to the jupyter_server module we use is to use what the main jupyter lite demo has as core modules https://github.com/jupyterlite/demo/blob/0cddee229c47161aadc17e836ca0b78f991a7908/requirements.txt#L2

Fixes # (issue)

Type of change

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• Bug fix
• New feature
• Requires documentation updates

Testing

Please describe the test(s) that you added and ran to verify your changes.

Checklist

• I have read the contribution guide recently

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 70.96%. Comparing base (26b9367) to head (518b679).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #449   +/-   ##
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  Coverage   70.96%   70.96%           
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  Files           9        9           
  Lines        3541     3541           
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  Hits         2513     2513           
  Misses       1028     1028