[MDBViz] Switch from a QListView to a QTreeView for the ops

This lets us open & close groups and automates the hierarchy.

Change-Id: Ib6f0850a49b793d824fc25aa16be78e6a1a93d9e
Reviewed-on: https://skia-review.googlesource.com/43280
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/BUILD.gn b/BUILD.gn
index 6796850..1c328b0 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -1736,6 +1736,7 @@
       ]
       include_dirs = [
         "$skia_qt_path/include",
+        "$skia_qt_path/include/QtCore",
         "$skia_qt_path/include/QtWidgets",
         "tools",
         "tools/debugger",