Getting Live View to work with Javascript Hooks

Live View Hooks Example

### In App.js initialize the hook and set it on the LiveSocket
### Tested with LiveView 0.15.7
```
Hooks.MyHook = {
  mounted() {
    console.log("MyHook.mounted")
  },
  updated() {
    console.log("MyHook.updated")
  }
}

let csrfToken = document.querySelector("meta[name='csrf-token']").getAttribute("content")
let liveSocket = new LiveSocket("/live", Socket, {hooks: Hooks, params: {_csrf_token: csrfToken}})
```
### In Your Leex file, add the attribute for the hook. This can go on any element that will be changed via the LiveView.
```
<div id="chat-messages" phx-hook="MyHook">
```