InputControl: Make onChange observable in Storybook

[mirka]

Required for testing IME keydown handling (follow-up to #59081)

What?

Enhances the Storybook stories for InputControl so onChange events can be tested using the Actions panel.

Why?

We generally want all our onChange events to be testable in Storybook.

Testing Instructions

In trunk Storybook, we can see that change events aren't logged in the Actions panel.

1. In local Storybook for this PR, the change events should now be logged as expected.
2. Enable the control for the isPressEnterToChange prop and reload.
3. The onChange should only be logged after blurring the input or hitting the Enter key. The onValidate calls should also be logged.

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Co-authored-by: mirka <0mirka00@git.wordpress.org>
Co-authored-by: tyxla <tyxla@git.wordpress.org>

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[tyxla]

Does the job 👍

Any concerns with this bit from Storybook docs?

This is quite useful when your component has dozens (or hundreds) of methods and you do not want to manually apply the fn utility for each of those methods. However, this is not the recommended way of writing actions. That's because automatically inferred args are not available as spies in your play function. If you use argTypesRegex and your stories have play functions, you will need to also define args with the fn utility to test them in your play function.

I personally don't have concerns about tracking them all, was just curious if you had any thoughts about it.

Note: unit test failures are unrelated and should disappear after a rebase.

[mirka]

This information is new to me, thanks for surfacing! I don't foresee us using Play functions in this main Storybook instance, so I think the convenience of the catch-all still outweighs the potential downsides. In this PR too, I likely would've forgotten onValidate if it weren't for the catch-all. But I have no issue with going back to explicit declarations if we start to encounter problems down the line 👍