Reorganize static folder and add pre-loaded stylesheets

[edan-bainglass]

This PR reorganizes the static folder with dedicated subfolders for templates and styles. The styles folder holds stylesheets that are automatically loaded (using a new aiidalab-widgets-base utility function) in the main notebook.

Dependency

This PR depends on aiidalab/aiidalab-widgets-base#624, which introduces the load_css utility

[codecov]

Codecov Report

Attention: Patch coverage is 75.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 68.16%. Comparing base (772878b) to head (65327d9).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/aiidalab_qe/app/result/workchain_viewer.py	50.00%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #772   +/-   ##
=======================================
  Coverage   68.16%   68.16%           
=======================================
  Files          48       48           
  Lines        4159     4159           
=======================================
  Hits         2835     2835           
  Misses       1324     1324           

Flag	Coverage Δ
python-3.11	68.16% <75.00%> (ø)
python-3.9	68.19% <75.00%> (ø)

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[edan-bainglass]

@danielhollas, @superstar54, @yakutovicha the silicon select and confirm test is timing out. I tried to commit an increase to the timeout (to 60s), but it still is not enough. I'm surprised the new CSS loading or the reorganization of static files could cause such a delay. Could someone please give it a look?

[edan-bainglass]

Resolved. Thanks @superstar54 🙂

[danielhollas]

Looks reasonable, only one comment about the outdated README file. Leaving approval to others.