Merge bitcoin/bitcoin#24356: refactor: replace CConnman::SocketEvents() with mockable Sock::WaitMany()

6e68ccbefe net: use Sock::WaitMany() instead of CConnman::SocketEvents() (Vasil Dimov)
ae263460ba net: introduce Sock::WaitMany() (Vasil Dimov)
cc74459768 net: also wait for exceptional events in Sock::Wait() (Vasil Dimov)

Pull request description:

  _This is a piece of #21878, chopped off to ease review._

  `Sock::Wait()` waits for IO events on one socket. Introduce a similar `virtual` method `WaitMany()` that waits simultaneously for IO events on more than one socket.

  Use `WaitMany()` instead of `CConnman::SocketEvents()` (and ditch the latter). Given that the former is a `virtual` method, it can be mocked by unit and fuzz tests. This will help to make bigger parts of `CConnman` testable (unit and fuzz).

ACKs for top commit:
  laanwj:
    Code review ACK 6e68ccbefe
  jonatack:
    re-ACK 6e68ccbefe per `git range-diff e18fd47 6747729 6e68ccb`, and verified rebase to master and debug build

Tree-SHA512: 917fb6ad880d64d3af1ebb301c06fbd01afd8ff043f49e4055a088ebed6affb7ffe1dcf59292d822f10de5f323b6d52d557cb081dd7434634995f9148efcf08f

src/i2p.cpp

@@ -150,8 +150,8 @@ bool Session::Accept(Connection& conn)
                 throw std::runtime_error("wait on socket failed");
             }
 
-            if ((occurred & Sock::RECV) == 0) {
-                // Timeout, no incoming connections within MAX_WAIT_FOR_IO.
+            if (occurred == 0) {
+                // Timeout, no incoming connections or errors within MAX_WAIT_FOR_IO.
                 continue;
             }