feat: add optional fullscreen button to Modal

[rpenido]

Description

This PR introduces an optional Fullscreen button on the ModalDialog class to enable users to toggle full-screen mode.

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Additional Info

This PR is part of an initiative to improve the UI for xblock editors with many configuration options.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.40%. Comparing base (dfc69e2) to head (65fc4a7).
⚠️ Report is 5 commits behind head on release-23.x.

Additional details and impacted files

@@               Coverage Diff                @@
##           release-23.x    #4118      +/-   ##
================================================
+ Coverage         94.39%   94.40%   +0.01%     
================================================
  Files               242      242              
  Lines              4296     4304       +8     
  Branches           1020      987      -33     
================================================
+ Hits               4055     4063       +8     
  Misses              237      237              
  Partials              4        4              

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