Stop FileWatcher default instance on dedicated server exit

This prevents the FileWatcher instance from blocking the JVM from
exiting normally, as the instance keeps alive a non-daemon thread (and
the JVM waits on all non-daemon threads to exit).

Fixes #1626

patches/net/minecraft/server/dedicated/DedicatedServer.java.patch

@@ -44,14 +44,17 @@
              return true;
          }
      }
-@@ -277,6 +_,10 @@
+@@ -277,6 +_,13 @@
          if (this.queryThreadGs4 != null) {
              this.queryThreadGs4.stop();
          }
 +        if (this.dediLanPinger != null) {
 +            this.dediLanPinger.interrupt();
 +            this.dediLanPinger = null;
 +        }
++
++        // Neo: Forcibly stop the FileWatcher default instance, to prevent it from blocking normal JVM exit; see #1626
++        com.electronwill.nightconfig.core.file.FileWatcher.defaultInstance().stop();
      }
 
      @Override