Add Onboarding flow MetaMask

[nicktaras]

https://docs.metamask.io/guide/onboarding-library.html#examples

This is a nice to have feature and something we'd like to develop and review how this feature can help bring new users to web3.

Things we are to resolve are:

• Which end user is this for. E.g. Existing metamask customers who wish to install the extension and get back to the website + new customers?
• How this best fits into the flow

[hboon]

Love how they have this section https://docs.metamask.io/guide/onboarding-library.html#examples "Using Vanilla Javascript + HTML" :)