Should ?exploreNumbers be public?

[arouinfar]

We recently updated the Teacher Tips template to include common code query parameters (phetsims/query-string-machine#52) and QA is working on updating all Teacher Tips (phetsims/qa#963). Part of this process involved QA reviewing all sims to see if there are public query parameters that should be included in the Teacher Tips.

The exploreNumbers query parameter is not currently public, but looks like something that would be helpful to teachers. From what I can tell, it was introduced in #151 to make it easier to test the limit of 9999 on the Explore Screen. It prepopulates the Explore screen with the specified numbers, for example:
https://phet.colorado.edu/sims/html/make-a-ten/latest/make-a-ten_all.html?exploreNumbers=99,236

The query parameter is generally well-behaved in the latest published version and on master. It has validation to make sure no individual number exceeds 9999. However, there isn't any validation that the sum of the numbers respects this maximum, so the sim can start to behave strangely if you try something like:
https://phet.colorado.edu/sims/html/make-a-ten/latest/make-a-ten_all.html?exploreNumbers=9999,9999,9999,9999

At some point in the future, this sim will be republished with the various updates introduced in counting-common. The design team should consider if exploreNumbers should be public-facing, and if so, if any further validation is necessary.

Since this sim isn't currently being worked on, I'll tag @amanda-phet @jonathanolson @marlitas, but won't assign.