Hold 0069's destination set and its redirect rule as values (#69)

.github/coverage/pinned-surface

@@ -78,6 +78,7 @@ module  src/session/device.rs       The device identity, whose identifier is one
 module  src/server/mod.rs           The server module and what it places at its own boundary.
 module  src/server/address.rs       The address a person typed, parsed and refused where it is not usable.
 module  src/server/certificate.rs   The one exception 0029 admits to certificate validation: which certificate an operator pinned for which server, and what a pin never vouches for. A defect here accepts a certificate nobody asserted was theirs, or turns one server's key into something that can answer for a name the person never typed.
+module  src/server/destinations.rs  0069's set of destinations, the comparison an origin is admitted by, and what a redirect leaving the origin a request was sent to does. A defect here follows a server's redirect out to a host nobody configured, which is an address and a device identity reaching somewhere the operator never chose, or admits a host on a core nothing has been configured on, where 0068 says the set is empty.
 module  src/server/federation.rs    Which second host a request may reach, and the deliberate act that admits one.
 module  src/server/recovery.rs      0045's schedule for a server that is gone: when the next probe is due, where the doubling stops, and the hour after which the core stops asking. A defect here is a radio kept busy overnight on a device in somebody's bag, or a server that came back and was noticed hours later.
 module  src/server/retry.rs        0038's one policy for every request the core makes: which kinds are retried inside a call, how many attempts one call may spend, the interval each wait is drawn over, and the deadline that ends it. A defect here retries something that changed the server, or keeps a caller waiting past the point 0007 says an answer is not coming.

src/lib.rs

@@ -141,6 +141,10 @@ const _: () = {
     any_thread::<diagnostics::redaction::Correlator>();
     any_thread::<server::QueryResult>();
     any_thread::<server::federation::Federation<'static>>();
+    any_thread::<server::destinations::Destinations>();
+    any_thread::<server::destinations::AdmittedOrigin>();
+    any_thread::<server::destinations::WhatConfiguringDid>();
+    any_thread::<server::destinations::WhatARedirectDoes>();
     any_thread::<server::certificate::Fingerprint>();
     any_thread::<server::certificate::PresentedChain<'static>>();
     any_thread::<server::certificate::Refused<'static>>();