Reorganize directories (#3462)

* 🚚 move files
* 🚚 rename doc folder to docs
* 🚚 rename test folder to tests

tests/thirdparty/Fuzzer/test/EmptyTest.cpp

@@ -0,0 +1,11 @@
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+// A fuzzer with empty target function.
+
+#include <cstdint>
+#include <cstdlib>
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
+  return 0;
+}