[ENH] add "visual correction" and "head stabilization" metadata

[Remi-Gau]

closes #1531

• adds HeadStabilization to StimulusPresentation in events.json
• adds VisualAids in events.json

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (bdc3d55) 87.83% compared to head (395a699) 87.83%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1539   +/-   ##
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  Coverage   87.83%   87.83%           
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  Files          16       16           
  Lines        1356     1356           
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  Hits         1191     1191           
  Misses        165      165           

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[effigies]

"Visual aid" is something that presents information visually. It is rarely-to-never used to refer to corrective eyewear. Would VisionCorrection work?

Otherwise, this seems fine.

[Remi-Gau]

"Visual aid" is something that presents information visually. It is rarely-to-never used to refer to corrective eyewear. Would VisionCorrection work?

yes that would make sense to me: will ping some of the people on the eyetracking BEP to make sure that it is good with them too.

[effigies]

Works for me. I assume the eye tracking bep has had a chance to object.