LookupServer: Move case randomization into DNSName

* DNSName knows how to randomize itself
* DNSPacket no longer constructs DNSQuestion instances, it receives an already
  built DNSQuestion and just adds it to the list
* LookupServer::lookup() explicitly calls randomize_case() if it needs to
  randomize the case.

Userland/Services/LookupServer/DNSName.h

@@ -41,6 +41,8 @@ public:
     size_t serialized_size() const;
     const String& as_string() const { return m_name; }
 
+    void randomize_case();
+
 private:
     String m_name;
 };