Reconnection is directed by `BotOfflineEvent`.
### Event Broadcasting
- PacketFactory `MessageSvcPushForceOffline` closes network with `ForceOfflineException`.
- `network.close(cause)` pass the cause to state observer from `QQAndroidBot.stateObserverChain`, the observer broadcasts as follows:
- Nothing if `cause` is `ForceOfflineException` or `BotClosedByEvent`(which is broadcast by user)
- `BotOfflineEvent.Dropped` if cause is NetworkException and is recoverable(which is from Netty handlers)
- `BotOfflineEvent.Force` if cause is `ForceOfflineException` is from the factory mentioned above.
- `BotOfflineEvent.Active` otherwise(any other unexpected exceptions considered as an error)
### Deciding whether to reconnect
User can listen and change `BotOfflineEvent.reconnect` to decide. Default values are determined by `BotConfiguration`.
### Event listening
- Component `BotOfflineEventMonitor` listens `BotOfflineEvent`, logs the event for users, and launches a coroutine to do `network.resumeConnection` to notify the selector to renew an instance.
- `BotOnlineWatchdog` in `SelectorNetworkHandler` is removed.
- Selector now handles `maxAttempts` correctly in such a way that `awaitResumeInstance` does not throw exception until maximum attempts reached.
- On every attempt, new exceptions are logged to provide debugging information, and further duplications are ignored.
- Remove `FactoryKeepAliveNetworkHandlerSelector` and add `KeepAliveNetworkHandlerSelector`;
- Review the storage of `QQAndroidBotClient`, extract it as a `BotClientHolder`;
- Introduce bot-level components that lasts with the lifecycle of `Bot`, and network-level components accordingly;
- Dynamically re-create the context given to `NetworkHandler` in selector, to use network-level components, including `BotClientHolder`, that allows a simple reinitialization of `BotClient`;
- Handles the situation when physical network broken on logging in, giving a hint to user and halts the log-in process and transfer the responsibility of reconnecting to selector;
- Send logout only in `Bot.close` (manual close).
