Add preview section on events submission form

[starbelly]

Currently when submitting an event you don't get to see what that will look like until after the event is submitted and what's more approved. It would be quite nice to add a preview "pane" if you will that shows the two different ways your event will be displayed. Small card view (like on the front page of the site) and large card view (like when you go to https://erlef.org/events/).

This seems to be a great case for live view to me. A simple live render component would do it, I'm also not opposed to the entire form being redone in live view either.

[davydog187]

Started work on this in #321

I'm reworking the rendering of the public-facing event page such that it renders from a live view, which will probably delegate to something that the Admin can use for preview.