Add Tweet button to drives

Bear with me here...

So @VirtuallyChris just posted in the Discord asking for Tweets about openpilot, which got me thinking...
We have a bunch of stats (and could have more with #77), so we could create a [Tweet Button](https://developer.twitter.com/en/docs/twitter-for-websites/tweet-button/overview) pre-filled with something like:

> #openpilot just drove me x miles and I only touched the wheel y times

Could get real fancy and generate a mini infographic image too, and maybe use a screen grab from somewhere in the middle of the trip as the background? 😎