feat: Implement 34/WAKU2-PEER-EXCHANGE

[kaiserd]

This issue tracks the implemenation of 34/WAKU2-PEER-EXCHANGE.
It is part of the Ambient Peer Discovery Roadmap and the Waku Peer Exchange Milestone.

action items

• implement 34/WAKU2-PEER-EXCHANGE requester functionality feat: waku peer exchange (RFC34) #1152
• implement 34/WAKU2-PEER-EXCHANGE responder functionality feat: waku peer exchange (RFC34) #1152
• add test cases

[fryorcraken]

@kaiserd During the Vac PM call last week you mentioned that there are known limitations with the implementation that could be tackled at a later stage after some dog fooding.

Could you please update this issue with an executive summary of:

• the known limitations
• the expected/likely next steps once dogfooding is started.