Updating Websocket Protocol as per assetPrefix

[neeraj3029]

Problem:
When the browser location protocol is https, and the assetPrefix (link to CDN) corresponds to an http protocol (like http://localhost:3000 ), the websocket protocol is still determined only by browser's location, and becomes wss://. This will lead to an incorrect websocket protocol & URL (wss://localhost:3000/, for eg.)

Changes:

This PR updates the Websocket protocol as per the assetPrefix.

Bug

• Related issues linked using fixes Next v12 upgrade: WebSocket connection to 'wss://localhost:3000/_next/webpack-hmr' failed: for https connections vercel/next.js#31139
• Integration tests added
• Errors have helpful link attached, see contributing.md