LookupServer: Introduce DNSName

This is a wrapper around a string representing a domain name (such as
"example.com"). It never has a trailing dot.

For now, this class doesn't do much except wrap the raw string. Subsequent
commits will add or move more functionality to it.

Userland/Services/LookupServer/CMakeLists.txt

@@ -3,6 +3,7 @@ compile_ipc(LookupClient.ipc LookupClientEndpoint.h)
 
 set(SOURCES
     DNSAnswer.cpp
+    DNSName.cpp
     DNSPacket.cpp
     LookupServer.cpp
     LookupServerEndpoint.h