Migrate to Manifest version 3

[angelo-v]

Manifest version 2 is deprecated, and support will be removed in 2023. See https://developer.chrome.com/blog/mv2-transition/ for more details.

[angelo-v]

This is a much bigger issue than I anticipated, since background scripts are replaced by service workers and this also means support for localStorage is dropped. Localstorage is used by inrupt/oidc-client-js which is the fork of a deprecated library that is replaced by oidc-client-ts.

Brainstorming ideas how to proceed:

1. Get rid of localstorage in all transitive dependencies
2. Stay on v2 and loose chrome support in 2023 (what about other chromium browsers, will they keep v2 support?)
3. Migrate to a Firefox plugin
4. Find alternatives to service worker (e.g. popup.js, content script or even options page?)

Option 1 Get rid of localstorage in all transitive dependencies

• Migrate inrupt/solid-authn-client-js to use oidc-client-ts Migrate to oidc-client-ts (successor project of oidc-client-js) inrupt/solid-client-authn-js#2202
• Support chrome storage api in oidc-client-ts Is it possible to use oidc-client-ts in service worker? authts/oidc-client-ts#398