Availability Subsystems: bitfield distribution subsystem

[kishansagathiya]

Issue summary

This subsystem is responsible for gossiping bitfields created in other subsystems or received over the network.

Sub Issues

• bitfield distribution design and research #4232
• feat(dot/parachain): create skeleton for bitfield distribution subsystem #4234
• feat(dot/parachain/bitfield-distribution): handle DistributeBitfield message #4235

Other information and links

• node implementer's guide https://paritytech.github.io/polkadot-sdk/book/node/availability/bitfield-distribution.html#bitfield-distribution)
• polkadot sdk https://github.com/paritytech/polkadot-sdk/blob/7035034710ecb9c6a786284e5f771364c520598d/polkadot/node/network/bitfield-distribution/src/lib.rs#L222

[kishansagathiya]

Requires skeleton and thus sub-issues. Estimating it at 8, until additional details and sub-issues arrives.