This commit introduces collator side of the collator protocol. This is just a skeleton that
- implements the SubSystem interface for the new subsystem
- registers it
- add common methods like processMessage

linked to issue #3824

Subsystems needs to know about the peers in collation and validation protocol.
This commit
- adds logic to network package for emitting network events when a new peer joins or a peer disconnects.
- introduces a method to get a channel that will give us network events.
- make collator protocol validator side listen to these events and react to it by editing its peer data

Linked to issue #3515

Handling active leaves updates are quite important in collator protocol since
- It tells us which relay parents to remove or add
- which candidates to add or remove
- Most importantly it leads us to letting us know as a validator which parachain we are assigned to.

This commit add logic to react to active leaves update by
- updating view
- updating active leaves
- updating our parachain assignments

linked to issue #3515

Co-authored-by: Eclésio Junior <eclesiomelo.1@gmail.com>

Co-authored-by: Eclésio Junior <eclesiomelo.1@gmail.com>

…github.com:ChainSafe/gossamer into kishan/feat/active-leaves-update-collator-protocol

…ollator-protocol