Add forwardRef to CompanionWindow

[cbeer]

No description provided.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.52%. Comparing base (5daa657) to head (5dbdfc0).
Report is 6 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4074   +/-   ##
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  Coverage   94.52%   94.52%           
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  Files         313      313           
  Lines       14766    14766           
  Branches     2495     2496    +1     
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  Hits        13957    13957           
  Misses        804      804           
  Partials        5        5           

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[marlo-longley]

This looks good. I just learned that React 19 will allow for refs to be passed to functional components, and forwardRef will be deprecated. So the purpose of this PR, silencing the warning about passing refs to functional components, won't be relevant on the next version of React.

Starting in React 19, you can now access ref as a prop for function components:
https://react.dev/blog/2024/12/05/react-19#ref-as-a-prop

Anyway this PR seems important so that Mirador 4 doesn't have browser warnings. But won't be an issue down the line.