🐛 Use ReactDOM.render instead of hydrate when prerender is falsy

[jsbaltodano]

Allow react-rails to use ReactDOM.render in components created whose value for prerender is falsy (false, nil).

Summary

React gives a warning when a not pre-rendered component is not rendered using ReactDOM.render()
Following advise from #842
A new html option has been added to use between the ReactDOM methods render() or hydrate().

render()
prerender not set or set to a falsy value

hydrate()
truthy value and not :static

[BookOfGreg]

This is excellent, thanks for the contribution!
I'll make a small tweak to the changelog to reference the issue and this PR and add a ruby test for the new data attr after I merge this. Great help! 😁