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/slider/base/numericsliderbase.cpp

@@ -21,7 +21,7 @@
 
 #include "numericsliderbase.h"
 
-#include "common/qtutils.h"
+#include "oakutil/qtutils.h"
 #include "common/configwrapper.h"
 #include "core.h"
 

app/widget/slider/base/sliderbase.cpp

@@ -25,7 +25,7 @@
 #include <QEvent>
 #include <QMessageBox>
 
-#include "common/qtutils.h"
+#include "oakutil/qtutils.h"
 #include "core.h"
 #include "window/mainwindow/mainwindow.h"
 

app/widget/slider/base/sliderlabel.h

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

app/widget/slider/base/sliderladder.cpp

@@ -32,8 +32,8 @@
 #include <ApplicationServices/ApplicationServices.h>
 #endif
 
-#include "common/lerp.h"
-#include "common/qtutils.h"
+#include "oakutil/lerp.h"
+#include "oakutil/qtutils.h"
 #include "common/configwrapper.h"
 
 namespace olive

app/widget/slider/base/sliderladder.h

@@ -26,7 +26,7 @@
 #include <QTimer>
 #include <QWidget>
 
-#include "common/define.h"
+#include "oakutil/define.h"
 
 namespace olive
 {

app/widget/slider/floatslider.cpp

@@ -24,7 +24,7 @@
 #include <cmath>
 #include <QDebug>
 
-#include "common/decibel.h"
+#include "oakutil/decibel.h"
 
 namespace olive
 {