CppEditor: Move static symbol finder instance to CppTools

...to it can be reused by other clients more easily. Also, in a
follow-up change it will have a project part dependency that can be
cleared inside the CppModelManager more easily.

Change-Id: Ic9f2ce5212a94fd05ab0571e9ad99d0a25f5bc5c
Reviewed-by: Marco Bubke <marco.bubke@theqtcompany.com>

src/plugins/cpptools/cppmodelmanager.h

@@ -58,6 +58,7 @@ class BaseEditorDocumentProcessor;
 class CppCompletionAssistProvider;
 class CppEditorDocumentHandle;
 class CppIndexingSupport;
+class SymbolFinder;
 class WorkingCopy;
 
 namespace Internal {
@@ -161,6 +162,8 @@ public:
 
     void enableGarbageCollector(bool enable);
 
+    SymbolFinder *symbolFinder();
+
     static QSet<QString> timeStampModifiedFiles(const QList<Document::Ptr> &documentsToCheck);
 
     static Internal::CppSourceProcessor *createSourceProcessor();