TShock Security Escalation Exploit

### Impact
An issue with the way OTAPI manages client connections results in stale UUIDs remaining on `RemoteClient` instances after a player disconnects.

Because of this, if the following conditions are met a player may assume the login state of a previously connected player:
1. The server has UUID login enabled
2. An authenticated player disconnects
3. A subsequent player connects with a modified client that does not send the `ClientUUID#68` packet during connection
4. The server assigns the same `RemoteClient` object that belonged to the originally authenticated player to the newly connected player

### Patches
TShock 5.2.1 hotfixes this issue. A more robust fix will be made to OTAPI itself.

### Workarounds
Implement a RemoteClient reset event handler in a plugin like so:
```csharp
public override void Initialize()
{
On.Terraria.RemoteClient.Reset += RemoteClient_Reset;
}

private static void RemoteClient_Reset(On.Terraria.RemoteClient.orig_Reset orig, RemoteClient client)
{
client.ClientUUID = null;
orig(client);
}
```