Design and plan network-bridge to rely on `Network` and `NotificationService`

[EclesioMeloJunior]

Issue summary

• Currently parachain has the responsability to register its own protocol stream handlers
• The responsability to register protocol stream handlers should not be in the parachains package but in the network layer which should provide to the network bridge an API to be aware of any received message. That's the point of relying on NotificationService
• The Network interface is the API of network layer where resides the peer reputation and send request methods used by parachains subsystems.

Implementation details

• Basically the network bridge has its own Network Service interface implemenation that under the hood uses the NetworkService implementation of substrate client. What the network-bridge Network Service interface has differently is the start_request method that should be implemented as it requires the authority discovery as part of the logic and in the end uses substrate NetworkService interface to perform the raw p2p request.

Other information and links

• https://github.com/paritytech/polkadot-sdk/blob/3ff1b1db36260cbc47297ab753e2dcec1f5999fd/substrate/client/network/src/service/traits.rs#L893
• https://github.com/paritytech/polkadot-sdk/blob/21fbd6b59d37fd18a00d0ec4b6f72dc376d63010/polkadot/node/network/bridge/src/network.rs#L159

Acceptance criteria

[] Add AC's here..
[] Regression testing (if applicable)
[] New code is 60% covered with unit tests