Merge #20942: [refactor] Move some net_processing globals into PeerManagerImpl

6452190 net_processing: simplify MaybeSetPeerAsAnnouncingHeaderAndIDs args (Anthony Towns)
39c2a69 net_processing: move MaybeSetPeerAsAnnouncingHeadersAndIDs into PeerManagerImpl (Anthony Towns)
7b7117e net_processing: simplify ProcessGetData and FindTxForGetData args (Anthony Towns)
34207b9 net_processing: move FindTxForGetData and ProcessGetData to PeerManagerImpl (Anthony Towns)
d440848 net_processing: simplify PeerManageImpl method args (Anthony Towns)
a490f0a net_processing: move MarkBlockAs*, TipMayBeStale, FindNextBlocksToDL to PeerManagerImpl (Anthony Towns)
052d9bc net_processing: simplify AlreadyHaveTx args (Anthony Towns)
eeac506 net_processing: move AlreadyHaveTx into PeerManageImpl (Anthony Towns)
9781c08 net_processing: move some globals into PeerManagerImpl (Anthony Towns)

Pull request description:

  Turns some globals into member variables, and simplifies the parameter list for some of net_processing's internal functions. Mostly just serves as a code cleanup at this point.

ACKs for top commit:
  jnewbery:
    Code review ACK 6452190
  ariard:
    Code Review ACK 6452190, changes are pretty straightforward.
  MarcoFalke:
    Concept ACK 6452190 I have not reviewed this, but I left a comment 🐡

Tree-SHA512: 381361f9dbfeb851a5522ead3165ce1447a0f212ddea4b483aa38975559ee5ed03a4ba69c24fd69f36847a1eddfef05785f5cbb2fcec5fe50f8b336e8047c3b1

Author: MarcoFalke