fix: state setter for download aspect toggle

[slak44]

Context

Clicking the aspect ratio button in the ViewportDownloadForm fails due to an error. When shadowing a class member name in js, you can't use the shadowed name to initialize the shadowing variable.

Changes & Results

I fixed the syntax to avoid the error, and used the setter with callback, which should always be used when the new state depends on the current state in react.

Testing

Click the aspect ratio button, and it will now work.

Checklist

PR

• My Pull Request title is descriptive, accurate and follows the
  semantic-release format and guidelines.

Code

• My code has been well-documented (function documentation, inline comments,
  etc.)

Public Documentation Updates

• The documentation page has been updated as necessary for any public API
  additions or removals.

[codecov]

Codecov Report

Merging #3188 (97d24c3) into master (fe57c00) will decrease coverage by 0.74%.
The diff coverage is 2.05%.

@@            Coverage Diff             @@
##           master    #3188      +/-   ##
==========================================
- Coverage   12.68%   11.94%   -0.74%     
==========================================
  Files         306      306              
  Lines        8233     8437     +204     
  Branches     1593     1678      +85     
==========================================
- Hits         1044     1008      -36     
- Misses       5797     5943     +146     
- Partials     1392     1486      +94     

Impacted Files	Coverage Δ
...latform/core/src/DICOMSR/SCOORD3D/parseSCOORD3D.js	2.66% <0.00%> (-0.73%)	⬇️
.../core/src/DICOMSR/SCOORD3D/utils/addMeasurement.js	5.40% <ø> (ø)
...re/src/DICOMSR/SCOORD3D/utils/getRenderableData.js	1.72% <0.00%> (-0.07%)	⬇️
...orm/core/src/DICOMSR/parseDicomStructuredReport.js	7.50% <0.00%> (-1.60%)	⬇️
platform/core/src/classes/HotkeysManager.js	76.66% <0.00%> (ø)
platform/core/src/classes/StudyLoadingListener.js	1.03% <0.00%> (+0.01%)	⬆️
...latform/core/src/classes/metadata/StudyMetadata.js	1.25% <0.00%> (-0.04%)	⬇️
.../core/src/measurements/tools/dicomSRDisplayTool.js	50.00% <0.00%> (ø)
...udies/services/wado/getReferencedSeriesSequence.js	7.69% <0.00%> (-0.65%)	⬇️
.../src/studies/services/wado/studyInstanceHelpers.js	1.56% <0.00%> (-0.48%)	⬇️
... and 25 more

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