add `twitch_poll_listener` & enhance poll example

[merlinseela]

adding a twitch_poll_listener class inspired by the already implemented twitch_event_ listener, twitch_redeem_listener, (list is not exhaustive)

ones done -> enhance poll example:

• buttons for canceling, deleting (as in twitch UI)
• active poll live view
• live view has to work even if a poll is started before the example was loaded