Knobs: allow arrays in object knob proptypes

[Hypnosphi]

Issue: #810

This removes false positive warning when the value of object knob is an array

[codecov]

Codecov Report

Merging #1701 into release/3.3 will not change coverage.
The diff coverage is 0%.

@@             Coverage Diff              @@
##           release/3.3    #1701   +/-   ##
============================================
  Coverage        23.13%   23.13%           
============================================
  Files              253      253           
  Lines             5745     5745           
  Branches           686      680    -6     
============================================
  Hits              1329     1329           
+ Misses            3932     3931    -1     
- Partials           484      485    +1

Impacted Files	Coverage Δ
addons/knobs/src/components/types/Object.js	5.81% <0%> (ø)	⬆️
lib/ui/src/modules/ui/libs/hierarchy.js	50.74% <0%> (ø)	⬆️
lib/codemod/src/transforms/update-addon-info.js	51.16% <0%> (ø)	⬆️
addons/events/src/components/Event.js	0% <0%> (ø)	⬆️
.../ui/src/modules/ui/components/layout/dimensions.js	15.62% <0%> (ø)	⬆️
addons/info/src/components/PropTable.js	21% <0%> (ø)	⬆️
...react-native/src/manager/components/PreviewHelp.js	0% <0%> (ø)	⬆️
app/react-native/src/bin/storybook-build.js	0% <0%> (ø)	⬆️
addons/knobs/src/components/PropField.js	10.86% <0%> (ø)	⬆️
...ents/stories_panel/stories_tree/tree_decorators.js	34.37% <0%> (ø)	⬆️
... and 17 more

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