Add LightHouse CI for the Community Website

[HarshCasper]

Description

The LightHouse CI should ideally:

• Add lighthousesrc.json to identify the metrics we are looking to track.
• Use the aaron-binary/vercel-preview-url-action@v0.0.3 action to grab the deployed preview link.
• Use the treosh/lighthouse-ci-action to audit the preview link through LightHouse and upload generated files as artifact.
• Use the actions/github-script and marocchino/sticky-pull-request-comment to mark the performance as a PR comment.

Some inspiration can be fetched from the following PR by @sarthakkundra on Docusaurus:

• feat(v2): Added Lighthouse CI to PR checks facebook/docusaurus#3761

Note that it is using Netlify previews, instead of standard Vercel previews and it can be tweaked further for our use-case.

[rutujaingole]

@HarshCasper I'd like to work on this.