Provide a way to add historically accessed domains to the app allow-list.

[bgshacklett]

As an end-user, I would like to be able to choose domains to be added to the application allow-list from a list of previously accessed domains, so that I can ensure that all required URLs may be opened within the PWA browser, while opening out-of-scope URLs via my default browser.

One particular example where this would be helpful is with applications which require login via OAuth, or similar technologies. The authentication URLs may not be within the application scope, but must still be opened within the PWA browser for the authentication flow to succeed.