feat: allow override of plugin.modal height

[muselesscreator]

The height of the modal in modal.plugin call from the Unit defaults to 100vh, which can lead to visual issues with consumed interfaces. This allows the consumer to pass a height field (preferrably still in vh) that will be respected when creating the modal.

Without overridden height:

With overridden height:

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (f58d6d6) 87.86% compared to head (9eda837) 87.87%.
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1184   +/-   ##
=======================================
  Coverage   87.86%   87.87%           
=======================================
  Files         263      263           
  Lines        4483     4485    +2     
  Branches     1133     1133           
=======================================
+ Hits         3939     3941    +2     
  Misses        530      530           
  Partials       14       14           

Files Changed	Coverage Δ
.../courseware/course/sequence/Unit/ContentIFrame.jsx	95.00% <100.00%> (ø)
...e/course/sequence/Unit/hooks/useModalIFrameData.js	100.00% <100.00%> (ø)

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