ClangTools: Add tool that runs clang-tidy and clazy

... over the whole project.
Generate and read serialized files to get diagnostics.

Change-Id: Iafc25fc70443107a040a995efc038aed35102bbf
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>

src/plugins/clangtools/clangtoolsdiagnosticmodel.cpp

@@ -298,6 +298,8 @@ QVariant ExplainingStepItem::data(int column, int role) const
     }
     case Qt::ToolTipRole:
         return createExplainingStepToolTipString(m_step);
+    case Qt::DecorationRole:
+        return (m_step.message.startsWith("fix-it:")) ? iconData("fix-it") : QVariant();
     default:
         return QVariant();
     }