Reorganize directories (#3462)

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

tests/thirdparty/Fuzzer/test/DSO1.cpp

@@ -0,0 +1,12 @@
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+
+// Source code for a simple DSO.
+
+int DSO1(int a) {
+  if (a < 123456)
+    return 0;
+  return 1;
+}
+
+void Uncovered1() { }