Input manager

[BIightning]

Implemented input events as discussed in #33.

Tested functionality with StreamDeck Plus and Mini.

[BIightning]

Thinking about it again, I am not sure if introducing lifetimes into the library by letting the Input Manager instance hold a mutable ref to a deck is a good idea, we could just move the deck into the manager, make it public and access it via manager.deck if we need it.

That would be much easier to use imo.

What do you think @ryankurte ?

[ryankurte]

hey overall looks good, i think you are correct about it is more straightforward to just pass the deck instance into the manager (so long as it remains optional as not to break existing uses), and if folks have more complex needs we can look at that in the future (or it can be implemented outside the library).