docs(Checkbox): minor rework to use hooks, better show controlled mode

[layershifter]

This PR updates CheckboxExampleRemoteControl & CheckboxExampleRadioGroup examples to use functional components & hooks. CheckboxExampleRemoteControl shows better work with controlled mode.

[github-actions]

size-limit report

Path	Size
bundle-size/dist/Button.size.js	58.76 KB (0%)
bundle-size/dist/Icon.size.js	25.21 KB (0%)
bundle-size/dist/Image.size.js	53.91 KB (0%)
bundle-size/dist/Modal.size.js	68.9 KB (0%)
bundle-size/dist/Portal.size.js	40.61 KB (0%)

[codecov-commenter]

Codecov Report

Merging #4328 (210f1ca) into master (96b8a6f) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #4328   +/-   ##
=======================================
  Coverage   99.75%   99.75%           
=======================================
  Files         180      180           
  Lines        3245     3245           
=======================================
  Hits         3237     3237           
  Misses          8        8           

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