Restructure the native module

Consolidate all code into the src folder

native/src/core/applet_stub.cpp

@@ -0,0 +1,10 @@
+#include <sys/stat.h>
+
+#include <magisk.hpp>
+#include <base.hpp>
+
+int main(int argc, char *argv[]) {
+    umask(0);
+    cmdline_logging();
+    return APPLET_STUB_MAIN(argc, argv);
+}