refactor: Remove mempool global from net

Summary:

This refactor does two things:
* Pass mempool in to PeerLogicValidation
* Pass m_mempool around where needed

Backport of core PR17997.

Test Plan:

ninja all check-all

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D8772