Migrate to Manifest V3

[yuhaofe]

Google is deprecating Manifest V2, this extension should migrate to Manifest V3 before 2023.

Migration Checklist

feature	V2	V3	status	alts
favicon	"chrome://favicon/" permission	chrome.favicon api	pending	online favicon grabbers Yandex Google DuckDuckGo
background	background pages	service workers	todo
...

[andreask1]

The favicon API has been available since v104: https://bugs.chromium.org/p/chromium/issues/detail?id=104102#c63
Example: https://github.com/GoogleChrome/chrome-extensions-samples/tree/main/api/favicon

I think there shouldn't be any need for a service worker for this extension.