Migrate Customization User Guide content

[droumis]

I moved most of the content into new How-to pages under Create Components > Style Components and Create Components > Arrange and Size Components. There wasn't much in terms of Background or Core Concept material. There may be some material that could also go into a reference, but we first need to align on the next step for reference material.

In both apply_css.md and load_icon.md, I added an admonition that says that the embedded code may not render on the page due to incompatibility with pyodide. I guess it could be some interaction with setting the panel configuration. This is just what I observed when built locally. Is this a bug or am I doing something incorrectly?

other previews:

[codecov]

Codecov Report

Merging #4290 (1bb30b2) into main (3086230) will increase coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #4290      +/-   ##
==========================================
+ Coverage   82.67%   82.69%   +0.01%     
==========================================
  Files         239      239              
  Lines       34393    34464      +71     
==========================================
+ Hits        28436    28499      +63     
- Misses       5957     5965       +8     

Flag	Coverage Δ
ui-tests	38.09% <ø> (+0.07%)	⬆️
unitexamples-tests	73.76% <ø> (-0.05%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
panel/widgets/debugger.py	89.39% <0.00%> (-3.04%)	⬇️
panel/viewable.py	66.04% <0.00%> (-2.17%)	⬇️
panel/models/tabulator.py	96.70% <0.00%> (-1.10%)	⬇️
panel/util/__init__.py	86.66% <0.00%> (-0.45%)	⬇️
panel/tests/widgets/test_tables.py	99.67% <0.00%> (+<0.01%)	⬆️
panel/tests/ui/widgets/test_tabulator.py	98.99% <0.00%> (+0.01%)	⬆️
panel/widgets/tables.py	88.27% <0.00%> (+0.13%)	⬆️
panel/io/server.py	75.14% <0.00%> (+0.18%)	⬆️
panel/tests/conftest.py	89.36% <0.00%> (+0.27%)	⬆️
panel/io/cache.py	82.66% <0.00%> (+0.44%)	⬆️
... and 3 more

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[philippjfr]

Looks great, thank you! I'll look at the issues you raised separately. One last thing, could you please remove the Customization.ipynb now that you've migrated the contents.

[philippjfr]

Okay, I removed it. Thanks again!