Convert server to an Android project

To simplify the device server-side build, use gradle to create an APK,
even if we use it as a simple jar, by running its main() method.

server/src/main/java/com/genymobile/scrcpy/wrappers/DisplayManager.java

@@ -0,0 +1,28 @@
+package com.genymobile.scrcpy.wrappers;
+
+import android.os.IInterface;
+
+import com.genymobile.scrcpy.DisplayInfo;
+import com.genymobile.scrcpy.Size;
+
+public class DisplayManager {
+    private final IInterface manager;
+
+    public DisplayManager(IInterface manager) {
+        this.manager = manager;
+    }
+
+    public DisplayInfo getDisplayInfo() {
+        try {
+            Object displayInfo = manager.getClass().getMethod("getDisplayInfo", int.class).invoke(manager, 0);
+            Class<?> cls = displayInfo.getClass();
+            // width and height already take the rotation into account
+            int width = cls.getDeclaredField("logicalWidth").getInt(displayInfo);
+            int height = cls.getDeclaredField("logicalHeight").getInt(displayInfo);
+            int rotation = cls.getDeclaredField("rotation").getInt(displayInfo);
+            return new DisplayInfo(new Size(width, height), rotation);
+        } catch (Exception e) {
+            throw new AssertionError(e);
+        }
+    }
+}