ClangTools: Add diagnostic mark class

These marks can now be disabled.
This greys out the annotation color and the icon of the mark.

Change-Id: I5af4591db4baaaef55c986252f77d5d977427b56
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/clangtools/clangtoolsutils.h

@@ -27,6 +27,8 @@
 
 #include <cpptools/clangdiagnosticconfig.h>
 
+#include <utils/optional.h>
+
 #include <QtGlobal>
 
 QT_BEGIN_NAMESPACE
@@ -39,6 +41,22 @@ namespace Debugger { class DiagnosticLocation; }
 namespace ClangTools {
 namespace Internal {
 
+class Diagnostic;
+
+enum class FixitStatus {
+    NotAvailable,
+    NotScheduled,
+    Scheduled,
+    Applied,
+    FailedToApply,
+    Invalidated,
+};
+
+QString createDiagnosticToolTipString(
+    const Diagnostic &diagnostic,
+    Utils::optional<FixitStatus> status = Utils::nullopt,
+    bool showSteps = true);
+
 QString createFullLocationString(const Debugger::DiagnosticLocation &location);
 
 QString hintAboutBuildBeforeAnalysis();