Create either a query or event-based API to allow controllers (particularly Tor Browser) to reliably get circuit information

Currently we can not get the address or type of a bridge by id/fingerprint if the bridge entry in torrc does not have the fingerprint string provided. This info is needed for the circuit display in Tor Browser, which currently just displays 'Bridge' without the address or type information.

Tor Browser currently gets the circuit display information by first requesting the circuit for a given first-party domain/nonce pair. This returns an array of fingerprints. We then get the list of bridges stored in the torrc file via GETCONF bridge. We compare each bridge's id to each node in the circuit. If a match if sound we know the node is a bridge and we display its information. Otherwise, we assume it is a relay and we query the information from tor via GETINFO ns/id/$fingerprint.

With the change in #32125 (moved) we now infer that if the GETINFO call fails, it's because the id we've received is actually a Bridge whose info we do not know.

Some possible options:

• Tor updates the torrc with the Bridge's fingerprint once it is known. Tor Browser's logic doesn't change but there will be a window when a user looking at the circuit display will just see 'Bridge' rather than the full set of information.
• Tor adds a new query API that allows us to get Bridge information in a similar fashion to how we currently get relay information. The repeated GETCONF for bridges goes away and we now for each id in the circuit, we just try querying bridge info and if that fails we then query relay info.
• Tor Browser listens for the 'figured out the fingerprint for this bridge event' (which I believe currently just logs?) and maintains some in-memory map/cache of fingerprint to { type, ip, geolocation }. I'd really rather not do this.
• Add a 'verbose' circuit query API, where we just provide the domain/nonce pair and you give us the required data all at once. This would simplify Tor Browser code and would require less back-and-forth between tor and Tor Browser.