Load index template resources from CDN

[philippjfr]

The index template was loading resources that were no longer bundled and also loading them from the /latest directory on the CDN which is note future proof. Here we align the handling with the main fast templates, upgrading to the recent version of fast-components and using our custom color handling implementation.

Fixes #4881

[codecov]

Codecov Report

Merging #4891 (015e5d0) into main (f623f59) will increase coverage by 0.02%.
The diff coverage is 100.00%.

❗ Current head 015e5d0 differs from pull request most recent head c7d456d. Consider uploading reports for the commit c7d456d to get more accurate results

@@            Coverage Diff             @@
##             main    #4891      +/-   ##
==========================================
+ Coverage   83.37%   83.39%   +0.02%     
==========================================
  Files         270      270              
  Lines       38130    38137       +7     
==========================================
+ Hits        31789    31804      +15     
+ Misses       6341     6333       -8     

Flag	Coverage Δ
ui-tests	40.84% <75.00%> (+0.02%)	⬆️
unitexamples-tests	73.36% <100.00%> (+<0.01%)	⬆️

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Impacted Files	Coverage Δ
panel/io/server.py	77.09% <100.00%> (+0.26%)	⬆️

... and 1 file with indirect coverage changes

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