[11.x] Pass iterable keys to withProgressBar in InteractsWithIO

[robinmoisson]

The withProgressBar method in the InteractsWithIO console trait can be used to iterate over an iterable while displaying a progress bar in the console, in essence adding a progress bar to a foreach loop.

Currently the callback only takes the $value of each step, which means it can't be used as easily if we want to unpack both $key and $value in each step.

This PR adds $key to the callback called in the foreach, transforming it from $callback($value, $bar) to $callback($value, $bar, $key), with arguments in that order to keep backward compatibility ($bar is the ProgressBar instance).

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I'm not sure if it's really necessary to update the progress bar docs to show that extra parameter, but if you think it'd be better I'd be happy to.