Move to the new GitHub Workflow to deploy the website to github pages

[rampatra]

Currently, this uses the traditional deploy to github pages method (you can see it in Settings > Github Pages). However, Github has introduced a new Workflow feature (still in Beta) that allows us to have more control of the deployment process. This task is to move to this new Workflow approach.

I have taken a stab at it here - https://github.com/rampatra/wedding-website/blob/master/.github/workflows/npm-gulp.yml, however, there are some issues that need to be resolved and should be done as part of this ticket. Once done, we can get rid of the fallback approach in index.html for node_modules.