Add PWA Support

[annardini]

With some of my projects, I have considered adding support for Progressive Web Apps (PWA) which allows for web apps to be installed onto devices and allows users to interact with the web apps like they would native applications except that PWAs require less space to be installed, allows for push notifications, offline support and more.

It made me think, would Payload CMS benefit from adding PWA Support and eventually push notifications for those with admin roles or "subscribed" to a collection?

Each project would have to be uploaded to the respective app stores which the docs may need to cover but it may be an idea for a future version. What does everybody else think?