Add an "array strategy" for first 3 screens

[amanda-phet]

Nancy noticed that when was trying to set the cup or plate values before they were visible, weird things happened (the default values overwrote the values she set, and some bars/apples became visible when they shouldn’t have).

@marlitas @Nancy-Salpepi and I discussed this and would like to move ahead with this idea, which @arouinfar approved of:

Create an "array strategy” (similar to kickDistributionStrategy) as a new element in the tree that lets the user set all cup/plate values, even if they aren’t visible. This would allow someone to pre-set all values for any screen even before they are visible. We would also change tableSnackNumberProperty to be read-only.

[Nancy-Salpepi]

tagging phetsims/qa#1121

[marlitas]

This is ready for @amanda-phet to review.

[marlitas]

It looks like @amanda-phet accidentally added feedback for this issue elsewhere. Here is what she said.

It's a little funky... For example, I set meanShareAndBalance.levelOutScreen.model.initialWaterLevelsProperty and the cups didn't come out how I set them, but I clicked reset and Set Value a few times and eventually things worked out. I think if I was more methodical I could figure out the sequence, but my overall question is just if clicking 'Set Value' should immediately set the value of all 7 cups, which I think it should, and that's not happening.

It seems to be working well on the Distribute and Faire Share screens!

@amanda-phet let me know if I put the feedback in the wrong issue.

[marlitas]

I met with @amanda-phet and we found a way to reproduce:

1. Navigate to the Level Out Screen in Studio.
2. Set meanShareAndBalance.levelOutScreen.model.initialWaterLevelsProperty to: [ 0.75,0.5,0,0.65,0.9,0.35,0.75]
3. Add a third cup in the sim. Notice that the third cup is not a value of 0.

[marlitas]

Due to a small oversight I was not iterating over all cups, only active cups which was causing the behavior. That should be fixed. @amanda-phet can you take a look now and make sure behavior is as expected? I can then mark for cherry-pick.

[amanda-phet]

It's working! Thanks!

[marlitas]

Great! Ready for cherry-pick.

[Nancy-Salpepi]

The array strategies are working nicely! Closing.