add check for online access when drawing panels

[BradyAJohnston]

Adds a check that disables the panel and displays a warning for the wwPDB and AlphaFold download panels if networking disabled.

[codecov]

Codecov Report

Attention: Patch coverage is 9.09091% with 10 lines in your changes missing coverage. Please review.

Project coverage is 71.54%. Comparing base (bb35110) to head (190a2c9).
Report is 7 commits behind head on main.

Files with missing lines	Patch %	Lines
molecularnodes/entities/molecule/ui.py	9.09%	10 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #590      +/-   ##
==========================================
- Coverage   71.73%   71.54%   -0.20%     
==========================================
  Files          50       50              
  Lines        4143     4157      +14     
==========================================
+ Hits         2972     2974       +2     
- Misses       1171     1183      +12     

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