getPairingAuthorityUrl

open override fun getPairingAuthorityUrl(): String

Get the URL at which to begin a device-pairing signin flow.

If the user wants to sign in using device pairing, call this method and then direct them to visit the resulting URL on an already-signed-in device. Doing so will trigger the other device to show a QR code to be scanned, and the result from said QR code can be passed to FirefoxAccount::begin_pairing_flow.