Clang: Rename TranslationUnit(s) to Document(s)

The "TranslationUnit parts" moved already to TranslationUnitCore.

Change-Id: I2bea7847e2b3e84fbfacc3d2dc43f180873349ac
Reviewed-by: David Schulz <david.schulz@qt.io>

src/tools/clangbackend/ipcsource/clangcompletecodejob.h

@@ -26,7 +26,7 @@
 #pragma once
 
 #include "clangasyncjob.h"
-#include "clangtranslationunit.h"
+#include "clangdocument.h"
 
 #include <clangbackendipc/codecompletion.h>
 
@@ -47,7 +47,7 @@ public:
     void finalizeAsyncRun() override;
 
 private:
-    TranslationUnit m_pinnedTranslationUnit;
+    Document m_pinnedDocument;
 };
 
 } // namespace ClangBackEnd