Go full wizard 🧙

[heff]

Taking inspiration from Sentry's setup tool, it would be great to take the init process a step further and do more for the user.

• [x] npx command does npm install
• [x] Add video.d.ts to tsconfig.json
• [x] Add withNextVideo to next.config.js
• [x] Add next-video sync -w to dev script in package.json
• [ ] Open Mux signup page
• [ ] Open access token creation page
• [ ] Prompt for token details and add to .env.local
• [ ] Add example video file to /videos to test the setup
• [ ] Add a demo page to the project to verify it's all working
• [ ] Create a "Manual Setup" page and direct people there if they're not comfortable with the wizard, or if something goes wrong.

It would be more magic if we could generate an access token without going to the Mux dashboard. I don't think we should try to get around signup through the dashboard.

[heff]

We should add messaging for what to do next at the end of wizard, otherwise it's an awkward drop off at the end of it.

Currently the next step is signing up and creating the .env.local file, which is an important one not to miss.