feat: add support for phx-change event on input

[StephanH90]

Currently, phx-change only works on form elements. This PR adds the functionality to also test this on inputs.

[germsvel]

Thanks for this work @StephanH90! 🎉

A quick follow up question. This is something we would also want to support for checkboxes and radio buttons, right?

It doesn't have to be done as part of this PR (we can open an issue for the others), but I just want to make sure so we can have consistent behavior across inputs.

[StephanH90]

Yes, I think you are right. It's up to you if you want me to do it as part of this PR as separate commits (then the title would be fitting, now the title is incorrect) or as separate PRs.

[germsvel]

@StephanH90 I think we can get this merged in without the rest. And then we can work on the rest (once CI passes).

If you're up for adding support for checkboxes and radio buttons in a separate PR, that would be amazing. But if not, we can add an open issue and see if someone else has time to grab it.

[StephanH90]

@germsvel I added support for radios, checkboxes and selects as well and added corresponding tests.

[germsvel]

Thanks so much @StephanH90! 🎉