Rework the event system of sc-network (#1370)

This commit introduces a new concept called `NotificationService` which
allows Polkadot protocols to communicate with the underlying
notification protocol implementation directly, without routing events
through `NetworkWorker`. This implies that each protocol has its own
service which it uses to communicate with remote peers and that each
`NotificationService` is unique with respect to the underlying
notification protocol, meaning `NotificationService` for the transaction
protocol can only be used to send and receive transaction-related
notifications.

The `NotificationService` concept introduces two additional benefits:
  * allow protocols to start using custom handshakes
  * allow protocols to accept/reject inbound peers

Previously the validation of inbound connections was solely the
responsibility of `ProtocolController`. This caused issues with light
peers and `SyncingEngine` as `ProtocolController` would accept more
peers than `SyncingEngine` could accept which caused peers to have
differing views of their own states. `SyncingEngine` would reject excess
peers but these rejections were not properly communicated to those peers
causing them to assume that they were accepted.

With `NotificationService`, the local handshake is not sent to remote
peer if peer is rejected which allows it to detect that it was rejected.

This commit also deprecates the use of `NetworkEventStream` for all
notification-related events and going forward only DHT events are
provided through `NetworkEventStream`. If protocols wish to follow each
other's events, they must introduce additional abtractions, as is done
for GRANDPA and transactions protocols by following the syncing protocol
through `SyncEventStream`.

Fixes https://github.com/paritytech/polkadot-sdk/issues/512
Fixes https://github.com/paritytech/polkadot-sdk/issues/514
Fixes https://github.com/paritytech/polkadot-sdk/issues/515
Fixes https://github.com/paritytech/polkadot-sdk/issues/554
Fixes https://github.com/paritytech/polkadot-sdk/issues/556

---
These changes are transferred from
https://github.com/paritytech/substrate/pull/14197 but there are no
functional changes compared to that PR

---------

Co-authored-by: Dmitry Markin <dmitry@markin.tech>
Co-authored-by: Alexandru Vasile <60601340+lexnv@users.noreply.github.com>

Cargo.lock

@@ -4177,6 +4177,7 @@ dependencies = [
  "cumulus-relay-chain-interface",
  "cumulus-relay-chain-rpc-interface",
  "futures",
+ "parking_lot 0.12.1",
  "polkadot-availability-recovery",
  "polkadot-collator-protocol",
  "polkadot-core-primitives",
@@ -13268,6 +13269,7 @@ dependencies = [
  "pallet-transaction-payment-rpc-runtime-api",
  "parity-db",
  "parity-scale-codec",
+ "parking_lot 0.12.1",
  "polkadot-approval-distribution",
  "polkadot-availability-bitfield-distribution",
  "polkadot-availability-distribution",
@@ -15728,6 +15730,7 @@ dependencies = [
  "array-bytes 4.2.0",
  "arrayvec 0.7.4",
  "blake2 0.10.6",
+ "bytes",
  "futures",
  "futures-timer",
  "libp2p-identity",
@@ -15793,6 +15796,7 @@ dependencies = [
  "tempfile",
  "thiserror",
  "tokio",
+ "tokio-stream",
  "tokio-test",
  "tokio-util",
  "unsigned-varint",
@@ -15848,10 +15852,12 @@ name = "sc-network-gossip"
 version = "0.10.0-dev"
 dependencies = [
  "ahash 0.8.3",
+ "async-trait",
  "futures",
  "futures-timer",
  "libp2p",
  "log",
+ "parity-scale-codec",
  "quickcheck",
  "sc-network",
  "sc-network-common",