Fix dlstbx and dodal environment in devcontainer

[olliesilvester]

Since the coper update, the devcontainer didn't install dodal as an editable dependency. dlstbx also wasn't being put into the python environment correctly. This fixes both

To test:

• Confirm that dodal is now an editable install after creating the devcontainer by typing uv pip freeze | grep dodal and seeing the -e flag
• Confirm that the dlstbx tests now run in the dev container environment, eg test_nexus_file_validity_for_zocalo_with_two_linked_datasets

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.85%. Comparing base (c69f4ee) to head (84af34b).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1621   +/-   ##
=======================================
  Coverage   92.85%   92.85%           
=======================================
  Files         153      153           
  Lines        8632     8632           
=======================================
  Hits         8015     8015           
  Misses        617      617           

Components	Coverage Δ
i24 SSX	78.60% <ø> (ø)
hyperion	98.22% <ø> (ø)
other	98.32% <ø> (ø)

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[adaudon]

Looks good 👍