Contain all rendering related tasks in DOMView.render()

[mattpap]

Currently rendering is spread in multiple places, including initialize(), connect_signals() and render(). When re-rendering this.el (the root element of a component) never gets recreated. It's "emptied" instead, but that doesn't really clear all the associated state with that element, which can cause issues when calling render() multiple times.

This PR moves all rendering related tasks to render() method, including creation of this.el. If re-rendering, then render() will create a new DOM element and then use replaceWith to efficiently replace it in the existing DOM hierarchy. This makes re-rendering much more predictable. Re-rendering, especially unnecessary re-rendering, is not advised, but sometimes necessary.