message: rpc: add ban_duration field to listbanned
diff: @@ -752,6 +752,7 @@ static RPCHelpMan listbanned()
  {RPCResult::Type::STR, "address", "The IP/Subnet of the banned node"},
  {RPCResult::Type::NUM_TIME, "ban_created", "The " + UNIX_EPOCH_TIME + " the ban was created"},
  {RPCResult::Type::NUM_TIME, "banned_until", "The " + UNIX_EPOCH_TIME + " the ban expires"},
  + {RPCResult::Type::NUM_TIME, "ban_duration", "The ban duration, in seconds"},
  }},
  }},
  RPCExamples{
  @@ -776,6 +777,7 @@ static RPCHelpMan listbanned()
  rec.pushKV("address", entry.first.ToString());
  rec.pushKV("ban_created", banEntry.nCreateTime);
  rec.pushKV("banned_until", banEntry.nBanUntil);
  + rec.pushKV("ban_duration", (banEntry.nBanUntil - banEntry.nCreateTime));
  bannedAddresses.push_back(rec);
  }
  