Merge bitcoin/bitcoin#27114: p2p: Allow whitelisting manual connections

0a533613fb docs: add release notes for #27114 (brunoerg)
e6b8f19de9 test: add coverage for whitelisting manual connections (brunoerg)
c985eb854c test: add option to speed up tx relay/mempool sync (brunoerg)
66bc6e2d17 Accept "in" and "out" flags to -whitelist to allow whitelisting manual connections (Luke Dashjr)
8e06be347c net_processing: Move extra service flag into InitializeNode (Luke Dashjr)
9133fd69a5 net: Move `NetPermissionFlags::Implicit` verification to `AddWhitelistPermissionFlags` (Luke Dashjr)
2863d7dddb net: store `-whitelist{force}relay` values in `CConnman` (brunoerg)

Pull request description:

  Revives #17167. It allows whitelisting manual connections. Fixes #9923

  Since there are some PRs/issues around this topic, I'll list some motivations/comments for whitelisting outbound connections from them:
  - Speed-up tx relay/mempool sync for testing purposes (my personal motivation for this) - In #26970, theStack pointed out that we whitelist peers to speed up tx relay for fast mempool synchronization, however, since it applies only for inbound connections and considering the topology `node0 <--- node1 <---- node2 <--- ... <-- nodeN`,  if a tx is submitted from any node other than node0, the mempool synchronization can take quite long.
  - https://github.com/bitcoin/bitcoin/pull/29058#issuecomment-1865155764 - "Before enabling -v2transport by default (which I'd image may happen after https://github.com/bitcoin/bitcoin/pull/24748) we could consider a way to force manual connections to be only-v1 or even only-v2 (disabling reconnect-with-v1). A possibility could be through a net permission flag, if https://github.com/bitcoin/bitcoin/pull/27114 makes it in."
  - https://github.com/bitcoin/bitcoin/pull/17167#issuecomment-1168606032 - "This would allow us to use https://github.com/bitcoin/bitcoin/pull/25355 when making outgoing connections to all nodes, except to whitelisted ones for which we would use our persistent I2P address."
  - Force-relay/mempool permissions for a node you intentionally connected to.

ACKs for top commit:
  achow101:
    ACK 0a533613fb
  sr-gi:
    re-ACK [0a53361](0a533613fb)
  pinheadmz:
    ACK 0a533613fb

Tree-SHA512: 97a79bb854110da04540897d2619eda409d829016aafdf1825ab5515334b0b42ef82f33cd41587af235b3af6ddcec3f2905ca038b5ab22e4c8a03d34f27aebe1

test/functional/test_framework/test_framework.py

@@ -96,6 +96,7 @@ class BitcoinTestFramework(metaclass=BitcoinTestMetaClass):
         """Sets test framework defaults. Do not override this method. Instead, override the set_test_params() method"""
         self.chain: str = 'regtest'
         self.setup_clean_chain: bool = False
+        self.noban_tx_relay: bool = False
         self.nodes: list[TestNode] = []
         self.extra_args = None
         self.network_thread = None
@@ -498,6 +499,10 @@ class BitcoinTestFramework(metaclass=BitcoinTestMetaClass):
             extra_confs = [[]] * num_nodes
         if extra_args is None:
             extra_args = [[]] * num_nodes
+        # Whitelist peers to speed up tx relay / mempool sync. Don't use it if testing tx relay or timing.
+        if self.noban_tx_relay:
+            for i in range(len(extra_args)):
+                extra_args[i] = extra_args[i] + ["-whitelist=noban,in,out@127.0.0.1"]
         if versions is None:
             versions = [None] * num_nodes
         if binary is None: