Open source stub APK loader

Close #3537

stub/src/main/java/a/c.java

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+package a;
+
+import com.topjohnwu.magisk.DownloadActivity;
+
+public class c extends DownloadActivity {
+}

stub/src/main/java/a/e.java

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+package a;
+
+import com.topjohnwu.magisk.DelegateApplication;
+
+public class e extends DelegateApplication {
+}

stub/src/main/java/a/h.java

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+package a;
+
+import com.topjohnwu.magisk.dummy.DummyReceiver;
+
+public class h extends DummyReceiver {
+}

stub/src/main/java/a/p.java

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+package a;
+
+import com.topjohnwu.magisk.FileProvider;
+
+public class p extends FileProvider {
+}