Merge #11740: Implement BIP159 NODE_NETWORK_LIMITED (pruned peers) *signaling only*

Merge #11740: Implement BIP159 NODE_NETWORK_LIMITED (pruned peers) *signaling only*

de74c62 [Doc] Update bip.md, add support for BIP 159 (Jonas Schnelli)
e054d0e [QA] Add node_network_limited test (Jonas Schnelli)
bd09416 Avoid leaking the prune height through getdata (fingerprinting countermeasure) (Jonas Schnelli)
27df193 Always set NODE_NETWORK_LIMITED bit (Jonas Schnelli)
7caba38 Add NODE_NETWORK_LIMITED flags and min block amount constants (Jonas Schnelli)

Pull request description:

  Extracted from #10387.
  Does implement BIP159, but only the signalling part. No connections are made to NODE_NETWORK_LIMITED in this PR.

  The address relay and connection work (the more complicated part) can then be separated (probably in #10387).

Tree-SHA512: e3218eb4789a9320b0f42dc10f62d30c13c49bdef00443fbe653bee22933477adcfc1cf8f6a95269324560b5721203ed41f3c5e2dd8a98ec2791f6a9d8346b1a