Improve server control and logging of the DOS blacklist (#10904)

* Log kicks related to DOS bans

* unBlacklistDos method

Added a method to remove an IP that was blacklisted for being a potential DOS attack.

* Added a command to add/remove/list DOS bans

* Switched from spaces to a tab in the subnet-ban command

Switched from spaces to a tab in the subnet-ban command's listing function. This is better for accessibility and customizability.

* Use info(String, Object...) instead of String.format

* Fixed formatting to fit style guidelines

core/src/mindustry/net/Administration.java

@@ -91,6 +91,10 @@ public class Administration{
         dosBlacklist.add(address);
     }
 
+    public synchronized void unBlacklistDos(String address){
+        dosBlacklist.remove(address);
+    }
+
     public synchronized boolean isDosBlacklisted(String address){
         return dosBlacklist.contains(address);
     }

core/src/mindustry/net/ArcNetProvider.java

@@ -113,6 +113,8 @@ public class ArcNetProvider implements NetProvider{
 
                 //kill connections above the limit to prevent spam
                 if((playerLimitCache > 0 && server.getConnections().length > playerLimitCache) || netServer.admins.isDosBlacklisted(ip)){
+                    Log.info("Closing connection @ - IP marked as a potential DOS attack.", ip);
+
                     connection.close(DcReason.closed);
                     return;
                 }