add shared dir to user's favorite list

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 5 lines in your changes missing coverage. Please review.

Project coverage is 45.22%. Comparing base (d7b442d) to head (101163c). Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
src/jupyterhub_config/custom_docker_spawner.py	0.00%	5 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #102 +/- ## ========================================== - Coverage 45.32% 45.22% -0.11% ========================================== Files 7 7 Lines 428 429 +1 ========================================== Hits 194 194 - Misses 234 235 +1 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.