Add an arrowOffset prop to apply responsive offset

[cloughy]

Hello,

I wanted to have an offset that would automatically apply on the proper side of the tooltip regarding its position with keepTooltipInside. I was not able to do it properly with offsetX and offsetY as it is applied independently of the tooltip position.

Thank you for any return you could raise me and thank you for your plugin

[cloughy]

@yjose is this looks good to you ? i might use directly a fork on my project but i was more more confortable to contribute on the main project. let me know if i miss something, if anything could be improved or refactored.