ClangCodeModel/TextEditor: Add support for highlighting parameters

This is already built into clang, so we just need to expose it to the
highlighter and the UI.

Fixes: QTCREATORBUG-24880
Change-Id: I6d0595af2589a9b69eb954aafad46457ab2c5752
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/clangcodemodel/clanghighlightingresultreporter.cpp

@@ -50,6 +50,8 @@ TextEditor::TextStyle toTextStyle(ClangBackEnd::HighlightingType type)
         return TextEditor::C_PRIMITIVE_TYPE;
     case HighlightingType::LocalVariable:
         return TextEditor::C_LOCAL;
+    case HighlightingType::Parameter:
+        return TextEditor::C_PARAMETER;
     case HighlightingType::Field:
     case HighlightingType::QtProperty:
         return TextEditor::C_FIELD;