Split apart debugger options pages, allow specifying a path to CDB.

Modify engine creation funcs to populate a list of option pages
to be able to handle engine enabling independently of the
actual engine creation.

src/libs/utils/pathchooser.h

@@ -82,6 +82,8 @@ public:
     /** Return the home directory, which needs some fixing under Windows. */
     static QString homePath();
 
+    void addButton(const QString &text, QObject *receiver, const char *slotFunc);
+
 private:
     // Returns overridden title or the one from <title>
     QString makeDialogTitle(const QString &title);