feat: button toggle: Allow consumer to control pressed state

[margaree]

Jira ticket

Problem:
Previously in the MVC toggle control, the on click event could happen prior to the pressed state being changed. With the switch to the component, that no longer happens. This was found to be an issue in discussions, where the consumer needs to click the button > accept a dialog > then the state should change.

Fix notes:
This allows the consumer to manage the state rather than managing the state through a click handler. Let me know alternative ideas and also alternative property names. I wasn't sure if there was another property with a similar function to model the name off of. Removed new property and switched to an event approach instead

To do:

• add vdiff test(s) if this approach seems good

[github-actions]

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[dlockhart]

These feel like they might be better suited to normal unit tests that just assert that the value of elem.pressed is what you're expecting.

[margaree]

It doesn't seem possible to @ignore our new click event since it's assigned to a variable, so this is our hack for not showing it in the docs (see this)

[d2l-github-release-tokens]

🎉 This PR is included in version 3.66.0 🎉

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• npm package (@latest dist-tag)

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[margaree]

Since this ends up triggering the click event listener on the button twice it's ending up a bit tricky LMS-side and in the meantime the double onclick is not a great behaviour (e.g., in discussions it's opening a double dialog). I'm going to rethink this a bit but might revert in the meantime (though it's possible no one one notice the weird behaviour)

[dbatiste]

I was thinking you might have to add a classInitializer and manage things from there instead of wiring up their functions to ButtonIcon.