Add new `descriptor` parameter that returns relays or bridges by digest of recently published descriptors
This suggestion is based on discussions with Sebastian related to legacy/trac#13135 (moved).
We should add a new parameter, let's call it
descriptor, that returns relays or bridges by the digest of recently published descriptors. This includes all kinds of descriptors published by relays/bridges, so server descriptors and extra-info descriptors, and descriptors derived from those by the directory authorities, namely microdescriptors. We probably don't have to support partial digests, but we might want to support both hex-encoded and base64-encoded digests.
Example request (not working yet):