Approval Checking Improvements Omnibus (#2480)

* add tracing to approval voting

* notify if session info is not working

* add dispute period to chain specs

* propagate genesis session to parachains runtime

* use `on_genesis_session`

* protect against zero cores in computation

* tweak voting rule to be based off of best and add logs

* genesis configuration should use VRF slots only

* swallow more keystore errors

* add some docs

* make validation-worker args non-optional and update clap

* better tracing for bitfield signing and provisioner

* pass amount of bits in bitfields to inclusion instead of recomputing

* debug -> warn for some logs

* better tracing for availability recovery

* a little av-store tracing

* bridge: forward availability recovery messages

* add missing try_from impl

* some more tracing

* improve approval distribution tracing

* guide: hold onto pending approval messages until NewBlocks

* Hold onto pending approval messages until NewBlocks

* guide: adjust comment

* process all actions for one wakeup at a time

* vec

* fix network bridge test

* replace randomness-collective-flip with Babe

* remove PairNotFound

polkadot/roadmap/implementers-guide/src/node/approval/approval-voting.md

@@ -135,7 +135,10 @@ struct State {
     session_info: Vec<SessionInfo>,
     babe_epoch: Option<BabeEpoch>, // information about a cached BABE epoch.
     keystore: KeyStorePtr,
-    wakeups: BTreeMap<Tick, Vec<(Hash, Hash)>>, // Tick -> [(Relay Block, Candidate Hash)]
+
+    // A scheduler which keeps at most one wakeup per hash, candidate hash pair and
+    // maps such pairs to `Tick`s.
+    wakeups: Wakeups, 
 
     // These are connected to each other.
     background_tx: mpsc::Sender<BackgroundRequest>,