Allow number inputs to be clicked and held

[derekthesnake]

This allows for the up/down buttons on number inputs to increment the values continually when they are held.

I migrated the click logic to a subfunction, and made the click function call itself every 250ms until the button is no longer held. It tracks the state by adding an HTML attribute to the buttons while they are held down.

This passes all tests and linting in GitHub Actions.

Addresses #8816.

[Zaczero]

Cool idea, I think the first delay should be slightly longer, e.g: 500ms, 250ms, 250ms, ….

I believe a solution using setInterval and clearInterval would be much cleaner and easier to follow:

setInterval(click_func, 250, d3_event, d)

If not, consider putting the recursive call after this line (for optimization):
https://github.com/openstreetmap/iD/pull/9462/files#diff-20bad07a0a50747d3c088cd4cfd32014b21edec39c11f9c71998bb0f46ef876cR92.

And don't make a proxy function just to pass the arguments, you can do it natively.