Feat: Copy `AUTH_URL` to clipboard

# Story

**As an `Engineer`** using **`auth`** 👩‍💻
**I want** to **`copy`** the [**`AUTH_URL`**](https://github.com/dwyl/auth/issues/277#issuecomment-1445010981) to my **`clipboard`** 📋
So that I can setup my `App` as fast as possible. 🏁

# Starting Point 😍

Thanks to @jeregrine we have a starting point for this:
https://fly.io/phoenix-files/copy-to-clipboard-with-phoenix-liveview
[ LAST UPDATED: JAN 25, 2023 ]

# Todo

Once we have shipped `V2` of `Auth` #207 we will:

+ [ ] Implement `copy-to-clipboard` buttons next to the [**`AUTH_URL`**](https://github.com/dwyl/auth/issues/277#issuecomment-1445010981) :shipit:
+ [ ] Figure out how to _test_ this so that we have some certainty that the feature always works. 🔍