Edit the Embedded Wallets, Wallets Aggregator quickstarts

[bgravenorst]

Update the Wallet Aggregator quickstarts for Vue, React, Next.js, Angular.

https://docs.metamask.io/quickstart/?product=EMBEDDED_WALLETS&framework=VUE&walletAggregatorOnly=YES&stepIndex=0

Note: Many of the steps have already been edited in previous PRs (due to content reuse).