chain, onThen, onCatch, onFinally should handle non-promise promise

[TwitchBronBron]

If you pass a non promise to promises.chain(), .onThen(), onCatch, onFinally(), it should convert any non-promises to promises rather than forcing the outside to promisify them. The developer's intent is to take that value and wait for it and run something in the callback, so it being a non-promise doesn't really matter.

This isn't a breaking change because previously it would throw an exception