Add option to disable Chrome's digital asset link checking

For a website to be shown in TWA mode, the digital asset links must check out.

For debugging, it is possible to get Chrome to skip the server -> app part of the Digital Asset Link checking ([info here](https://developers.google.com/web/android/trusted-web-activity/integration-guide) ). It would be great if we could have a `bubblewrap spoofVerification` command or something similar that does this.

(And equally, a command that undoes this afterwards.)