Port availability recovery to use req/res (#2694)

* add AvailableDataFetchingRequest

* rename AvailabilityFetchingRequest to ChunkFetchingRequest

* rename AvailabilityFetchingResponse to Chunk_

* add AvailableDataFetching request

* add available data fetching request to availability recovery message

* remove availability recovery message

* fix

* update network bridge

* port availability recovery to request/response

* use validators.len(), not shuffling

* fix availability recovery tests

* update guide

* Update node/network/availability-recovery/src/lib.rs

Co-authored-by: Bernhard Schuster <bernhard@ahoi.io>

* Update node/network/availability-recovery/src/lib.rs

Co-authored-by: Arkadiy Paronyan <arkady.paronyan@gmail.com>

* remove println

Co-authored-by: Bernhard Schuster <bernhard@ahoi.io>
Co-authored-by: Arkadiy Paronyan <arkady.paronyan@gmail.com>

polkadot/Cargo.lock

@@ -5407,6 +5407,7 @@ dependencies = [
  "futures-timer 3.0.2",
  "log",
  "lru",
+ "parity-scale-codec",
  "polkadot-erasure-coding",
  "polkadot-node-network-protocol",
  "polkadot-node-subsystem",
@@ -5414,11 +5415,11 @@ dependencies = [
  "polkadot-node-subsystem-util",
  "polkadot-primitives",
  "rand 0.8.3",
+ "sc-network",
  "smallvec 1.6.1",
  "sp-application-crypto",
  "sp-core",
  "sp-keyring",
- "streamunordered",
  "thiserror",
  "tracing",
 ]