[Feature Request] Add autofocus prop

[Andrew]

Please, add support for autofocus input behavior on component mounted by adding autofocus boolean prop

[Darren Jennings]

thanks for the feedback @AndrewBogdanovTSS. Closing re: #44 (comment)

In this scenario, it is a native element method .focus, which I think is better left for the user to implement in lieu of vue-autosuggest handling it via prop or otherwise.