Validator DHT (#494)

* Route validators for any active set through sc-authority-discovery

Additionally adds an RPC route to retrieve their P2P addresses.

* Have the coordinator get peers from substrate

* Have the RPC return one address, not up to 3

Prevents the coordinator from believing it has 3 peers when it has one.

* Add missing feature to serai-client

* Correct network argument in serai-client for p2p_validators call

* Add a test in serai-client to check DHT population with a much quicker failure than the coordinator tests

* Update to latest Substrate

Removes distinguishing BABE/AuthorityDiscovery keys which causes
sc_authority_discovery to populate as desired.

* Update to a properly tagged substrate commit

* Add all dialed to peers to GossipSub

* cargo fmt

* Reduce common code in serai-coordinator-tests with amore involved new_test

* Use a recursive async function to spawn `n` DockerTests with the necessary networking configuration

* Merge UNIQUE_ID and ONE_AT_A_TIME

* Tidy up the new recursive code in tests/coordinator

* Use a Mutex in CONTEXT to let it be set multiple times

* Make complimentary edits to full-stack tests

* Augment coordinator P2p connection logs

* Drop lock acquisitions before recursing

* Better scope lock acquisitions in full-stack, preventing a deadlock

* Ensure OUTER_OPS is reset across the test boundary

* Add cargo deny allowance for dockertest fork

substrate/validator-sets/pallet/src/lib.rs

@@ -124,8 +124,9 @@ pub mod pallet {
   #[pallet::getter(fn allocation_per_key_share)]
   pub type AllocationPerKeyShare<T: Config> =
     StorageMap<_, Identity, NetworkId, Amount, OptionQuery>;
-  /// The validators selected to be in-set who haven't been removed.
+  /// The validators selected to be in-set.
   #[pallet::storage]
+  #[pallet::getter(fn participants_for_latest_decided_set)]
   pub(crate) type Participants<T: Config> = StorageMap<
     _,
     Identity,