Add preliminary zygote code injection support

Prototyping the injection setup and a clean "self unloading" mechanism.

native/jni/inject/inject.hpp

@@ -0,0 +1,17 @@
+#pragma once
+
+#include <stdint.h>
+
+#define INJECT_LIB_1 "/dev/tmp/magisk.1.so"
+#define INJECT_LIB_2 "/dev/tmp/magisk.2.so"
+#define INJECT_ENV_1 "MAGISK_INJ_1"
+#define INJECT_ENV_2 "MAGISK_INJ_2"
+
+// Unmap all pages matching the name
+void unmap_all(const char *name);
+
+// Get library name and base address that contains the function
+uintptr_t get_function_lib(uintptr_t addr, char *lib);
+
+// Get library base address with name
+uintptr_t get_remote_lib(int pid, const char *lib);