Availability recovery subsystem (#2122)

* Adds message types

* Add code skeleton

* Adds subsystem code.

* Adds a first test

* Adds interaction result to availability_lru

* Use LruCache instead of a HashMap

* Whitespaces to tabs

* Do not ignore errors

* Change error type

* Add a timeout to chunk requests

* Add custom errors and log them

* Adds replace_availability_recovery method

* recovery_threshold computed by erasure crate

* change core to std

* adds docs to error type

* Adds a test for invalid reconstruction

* refactors interaction run into multiple methods

* Cleanup AwaitedChunks

* Even more fixes

* Test that recovery with wrong root is an error

* Break to launch another requests

* Styling fixes

* Add SessionIndex to API

* Proper relay parents for MakeRequest

* Remove validator_discovery and use message

* Remove a stream on exhaustion

* On cleanup free the request streams

* Fix merge and refactor

polkadot/Cargo.lock

@@ -4942,6 +4942,33 @@ dependencies = [
  "tracing-futures",
 ]
 
+[[package]]
+name = "polkadot-availability-recovery"
+version = "0.1.0"
+dependencies = [
+ "assert_matches",
+ "env_logger 0.8.2",
+ "futures 0.3.10",
+ "futures-timer 3.0.2",
+ "log",
+ "lru",
+ "polkadot-erasure-coding",
+ "polkadot-node-network-protocol",
+ "polkadot-node-subsystem",
+ "polkadot-node-subsystem-test-helpers",
+ "polkadot-node-subsystem-util",
+ "polkadot-primitives",
+ "rand 0.7.3",
+ "smallvec 1.6.1",
+ "sp-application-crypto",
+ "sp-core",
+ "sp-keyring",
+ "streamunordered",
+ "thiserror",
+ "tracing",
+ "tracing-futures",
+]
+
 [[package]]
 name = "polkadot-cli"
 version = "0.8.27"
@@ -5650,6 +5677,7 @@ dependencies = [
  "pallet-transaction-payment-rpc-runtime-api",
  "polkadot-availability-bitfield-distribution",
  "polkadot-availability-distribution",
+ "polkadot-availability-recovery",
  "polkadot-collator-protocol",
  "polkadot-network-bridge",
  "polkadot-node-collation-generation",