docs(list): add documentation to the List widget

[Valentin271]

Adds documentation to the List widget and all its sub components like ListState and ListItem

Relates to #386

Screenshots

List

ListItem

ListState

[codecov]

Codecov Report

Attention: 8 lines in your changes are missing coverage. Please review.

Comparison is base (dd22e72) 90.9% compared to head (6eb4966) 90.8%.
Report is 1 commits behind head on main.

Files	Patch %	Lines
src/widgets/list.rs	27.2%	8 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #669     +/-   ##
=======================================
- Coverage   90.9%   90.8%   -0.1%     
=======================================
  Files         42      42             
  Lines      12533   12545     +12     
=======================================
+ Hits       11394   11403      +9     
- Misses      1139    1142      +3     

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