Utils: Modernize further

Many issues, mostly in headers, were not addressed in
e38410b76c

modernize-use-auto
modernize-use-nullptr
modernize-use-override
modernize-use-using
modernize-use-default-member-init
modernize-use-equals-default

Change-Id: I320a51726db881e582b898948d53735ebb06887a
Reviewed-by: hjk <hjk@qt.io>

src/libs/utils/uncommentselection.h

@@ -50,7 +50,7 @@ public:
     bool hasMultiLineStyle() const;
 
 public:
-    bool isAfterWhiteSpaces;
+    bool isAfterWhiteSpaces = false;
     QString singleLine;
     QString multiLineStart;
     QString multiLineEnd;