Include button for launching jupyterlab layout in repr

[ian-r-rose]

This is an experimental UI element to help ease dashboard setup in a JupyterLab environment. Doesn't make sense to merge without a paired release of dask-labextension, but opening for discussion/visibility.

Edit: this is now ready for review, and works with dask-labextension==6.0.0.

[github-actions]

Unit Test Results

See test report for an extended history of previous test failures. This is useful for diagnosing flaky tests.

       15 files  +       15         15 suites  +15   6h 34m 14s ⏱️ + 6h 34m 14s
  3 169 tests +  3 169    3 084 ✔️ +  3 084    83 💤 +  83  2 ❌ +2 
23 448 runs  +23 448  22 544 ✔️ +22 544  900 💤 +900  4 ❌ +4 

For more details on these failures, see this check.

Results for commit 87e2dfe. ± Comparison against base commit a605d61.

♻️ This comment has been updated with latest results.

[gjoseph92]

Looking forward to this!

[mrocklin]

It looks like dask-labextension 6.0.0 is out. The CI failures are unrelated. Merging this in. Thank you @ian-r-rose

[mrocklin]

Question though: I often run JupyterLab in my base environment and then run Dask in a separate conda environment. In this case our code won't have dask-labextension in the same space. Correct? I think that this solution only works if I'm running Dask in the same environment where JLab is running. Correct?