Run a main looper in the cleanup process

Since a main looper is explicitly run in the main process, the
initialization of workarounds no longer calls
Looper.prepareMainLooper(), leading to a crash:

    java.lang.RuntimeException: Can't create handler inside thread
    Thread[main,5,main] that has not called Looper.prepare()

As a result, --power-off-on-close was broken.

Refs 283326b2f6
Fixes #6146 <https://github.com/Genymobile/scrcpy/issues/6146>

server/src/main/java/com/genymobile/scrcpy/CleanUp.java

@@ -7,6 +7,7 @@ import com.genymobile.scrcpy.util.SettingsException;
 import com.genymobile.scrcpy.wrappers.ServiceManager;
 
 import android.os.BatteryManager;
+import android.os.Looper;
 import android.system.ErrnoException;
 import android.system.Os;
 
@@ -179,6 +180,11 @@ public final class CleanUp {
         }
     }
 
+    @SuppressWarnings("deprecation")
+    private static void prepareMainLooper() {
+        Looper.prepareMainLooper();
+    }
+
     public static void main(String... args) {
         try {
             // Start a new session to avoid being terminated along with the server process on some devices
@@ -188,6 +194,9 @@ public final class CleanUp {
         }
         unlinkSelf();
 
+        // Needed for workarounds
+        prepareMainLooper();
+
         int displayId = Integer.parseInt(args[0]);
         int restoreStayOn = Integer.parseInt(args[1]);
         boolean disableShowTouches = Boolean.parseBoolean(args[2]);