Clang: Move unexported classes to Internal

Change-Id: I3ea197b734f146d4b11431aaf927aed9be7d8756
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: Ivan Donchevskii <ivan.donchevskii@qt.io>

src/plugins/clangcodemodel/clangfixitoperationsextractor.h

@@ -30,6 +30,7 @@
 #include <clangsupport/diagnosticcontainer.h>
 
 namespace ClangCodeModel {
+namespace Internal {
 
 class ClangFixItOperationsExtractor
 {
@@ -50,4 +51,5 @@ private:
     TextEditor::QuickFixOperations operations;
 };
 
+} // namespace Internal
 } // namespace ClangCodeModel