Pre-load component CSS

[philippjfr]

To make sure that by the time we render components all CSS resources are already cached we load all CSS files of the initially rendered components. Additionally we ensure that we now compile all CSS that directly corresponds to a single model, i.e. Plotly and Card.

[codecov]

Codecov Report

Attention: Patch coverage is 22.22222% with 21 lines in your changes are missing coverage. Please review.

Project coverage is 40.21%. Comparing base (c0585da) to head (2e64831).
Report is 2 commits behind head on main.

Files	Patch %	Lines
panel/template/base.py	0.00%	11 Missing ⚠️
panel/tests/test_server.py	20.00%	4 Missing ⚠️
panel/theme/base.py	0.00%	2 Missing ⚠️
panel/io/resources.py	66.66%	1 Missing ⚠️
panel/models/perspective.py	0.00%	1 Missing ⚠️
panel/pane/perspective.py	0.00%	1 Missing ⚠️
panel/tests/pane/test_holoviews.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #6563       +/-   ##
===========================================
- Coverage   82.97%   40.21%   -42.76%     
===========================================
  Files         313      313               
  Lines       46014    46021        +7     
===========================================
- Hits        38180    18508    -19672     
- Misses       7834    27513    +19679     

Flag	Coverage Δ
ui-tests	40.04% <22.22%> (-0.03%)	⬇️
unitexamples-tests	22.20% <11.11%> (-49.04%)	⬇️

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