Clean up app wrapper MVC

[edan-bainglass]

This PR cleans up recent developments in the app wrapper classes to better fit with the overall MVC design of the app.

Modifications

• Rename enable_toggles() to enable_controls(), as the top-level controls are no longer only toggle buttons
• Convert guide selectors options and values to AppWrapperModel state variables and sync
• Move observation handling to AppWrapperController
• Use AppWrapperController._open_external_notebook as a generic means of handling such events

Note regarding _open_external_notebook

#1011 actually discards this method in favor of anchor tags to avoid pop-up blocking.

[superstar54]

Could you fix the failed tests? Also please add some comments (on the github page directly, not inside the code) for the modification, this will help the review process.

[codecov]

Codecov Report

Attention: Patch coverage is 79.31034% with 6 lines in your changes missing coverage. Please review.

Project coverage is 69.12%. Comparing base (79b6201) to head (bf60746).

Files with missing lines	Patch %	Lines
src/aiidalab_qe/app/wrapper.py	79.31%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1009      +/-   ##
==========================================
+ Coverage   69.03%   69.12%   +0.09%     
==========================================
  Files         115      115              
  Lines        6388     6391       +3     
==========================================
+ Hits         4410     4418       +8     
+ Misses       1978     1973       -5     

Flag	Coverage Δ
python-3.11	69.12% <79.31%> (+0.09%)	⬆️
python-3.9	69.13% <79.31%> (+0.07%)	⬆️

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[edan-bainglass]

Could you fix the failed tests? Also please add some comments (on the github page directly, not inside the code) for the modification, this will help the review process.

Okay @superstar54. There you go 🙂 Please review 🙏

[superstar54]

LGTM!