R8 phase 1: extract app/engine shared utilities into shared/include/oakutil

Move the pure-header utilities shared by app/ and engine/ out of
engine/common/ into a new shared/include/oakutil/ layer (define, lerp,
decibel, digit, range, crashpadutils, autoscroll, qtutils, filefunctions
declarations, and a trimmed xmlutils exposing a CancelAtom-free void*
overload). engine/common/ keeps forwarding headers so internal include
paths are unchanged; app/ now includes oakutil/* directly.

engine/node/project.h gains an explicit NodeGroup forward declaration
previously obtained transitively through the old xmlutils.h.

app/widget/timelinewidget/timelinewidget.cpp

@@ -40,7 +40,7 @@
 #include "oakengine/audio.h"
 #include "core.h"
 #include "engineeventbridge.h"
-#include "common/range.h"
+#include "oakutil/range.h"
 #include "dialog/proxy/proxydialog.h"
 #include "dialog/sequence/sequence.h"
 #include "dialog/speedduration/speeddurationdialog.h"

app/widget/timelinewidget/tool/import.cpp

@@ -27,7 +27,7 @@
 #include <QToolTip>
 
 #include "common/configwrapper.h"
-#include "common/qtutils.h"
+#include "oakutil/qtutils.h"
 #include "core.h"
 #include "dialog/sequence/sequence.h"
 #include "node/audio/volume/volume.h"

app/widget/timelinewidget/tool/pointer.cpp

@@ -24,8 +24,8 @@
 #include <QDebug>
 #include <QToolTip>
 
-#include "common/qtutils.h"
-#include "common/range.h"
+#include "oakutil/qtutils.h"
+#include "oakutil/range.h"
 #include "common/configwrapper.h"
 #include "core.h"
 #include "node/block/gap/gap.h"

app/widget/timelinewidget/trackview/trackviewsplitter.h

@@ -24,7 +24,7 @@
 
 #include <QSplitter>
 
-#include "common/define.h"
+#include "oakutil/define.h"
 
 namespace olive
 {

app/widget/timelinewidget/view/timelineview.cpp

@@ -29,7 +29,7 @@
 #include <QPen>
 
 #include "common/configwrapper.h"
-#include "common/qtutils.h"
+#include "oakutil/qtutils.h"
 #include "../../timeruler/markerpainting.h"
 #include "node/project/footage/footage.h"
 #include "oakengine/timeline.h"