Service Worker API support

[mfulton26]

As a developer, I want to be able to write a service worker and use it both in clients (user agents / web browsers) and in servers.

If deno adds support for installing service workers with support for install, activate, fetch and other ServiceWorkerGlobalScope events then isomorphic service workers become a possibility.

[nayeemrmn]

Duplicate of #5957.

[mfulton26]

good call, as long as #5957 includes more than just the fetch event then I think we can close this issue in lieu of that one

thank you

[kitsonk]

Duplicate of #5957

[mfulton26]

@kitsonk will #5957 include install and activate events too or just fetch?

[kitsonk]

I will make that clear.

[mfulton26]

thank you!