Investigate deeplink scheme

Fenix registers fenix specific schema that allow another app to open a webpage in a specific Fenix variant (nightly, beta, release). https://gitlab.torproject.org/tpo/applications/fenix/-/blob/tor-browser-80.0b6-10-1/app/src/main/AndroidManifest.xml#L83

This assumes that the device doesn't have another app installed on it that advertises support for the requested schema, as well (because Android doesn't limit which schemas an app advertises). We should think about whether we should allow this behavior, and if we should continue using the fenix-specific schema and/or use a torbrowser-specific scheme.