🧹 Cleanup: put ABTestExample somewhere else

[reginawang3495]

https://github.com/uclaacm/Playnet/blob/main/src/components/Activities/Activity3/ABTestExample.tsx is really misleading, because its not an example

• Move to animations folder

• Rename to something like IntroABTestExplanations

• [ ] :wave: I may be able to implement this cleanup request

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This is a :broom: cleanup request

[reginawang3495]

closed by #190