Refactor RDTreeWidgetDelegate into RichTextViewDelegate that is reusable

* This allows us to add rich text support much more easily into other itemviews
  like RDTableView.
* We set it up for debug messages so that resource links in debug messages can
  be linked.

qrenderdoc/Windows/DebugMessageView.cpp

@@ -106,7 +106,12 @@ public:
           case 2: return sort ? QVariant((uint32_t)msg.severity) : QVariant(ToQStr(msg.severity));
           case 3: return ToQStr(msg.category);
           case 4: return msg.messageID;
-          case 5: return msg.description;
+          case 5:
+          {
+            QVariant desc = msg.description;
+            RichResourceTextInitialise(desc);
+            return desc;
+          }
           default: break;
         }
       }
@@ -208,6 +213,11 @@ DebugMessageView::DebugMessageView(ICaptureContext &ctx, QWidget *parent)
   ui->messages->setSortingEnabled(true);
   ui->messages->sortByColumn(0, Qt::AscendingOrder);
 
+  ui->messages->setMouseTracking(true);
+  ui->messages->setAutoScroll(false);
+
+  ui->messages->horizontalHeader()->setStretchLastSection(false);
+
   ui->messages->setContextMenuPolicy(Qt::CustomContextMenu);
   QObject::connect(ui->messages, &QWidget::customContextMenuRequested, this,
                    &DebugMessageView::messages_contextMenu);