[NUI] Manual merge from tizen50 (#653)

[NUI] Manual merge from tizen50 (#653)

Merged patches from tizenfx tizen_50 branch
- [NUI] Fix Svace issue (#534), Add to check Null value (View.cs)
- [NUI] Fix SizeWidth/Height issue (#555) (View.cs)
- [NUI] ResizePolicy UseNaturalSize mapped to WrapContent (#613) (View.cs)
- Improve the performance when firstly create the View (#642) (ImageView.cs, Scrollable.cs, TableView.cs, TextEditor.cs, TextField.cs, TextLabel.cs, VideoView.cs, View.cs)
- [NUI] Remove GL/VK if-else, reduce dll size (#649) (LayoutPINVOKE.cs, ManualPINVOKE.cs, NDalicPINVOKE.cs, NUIApplication.cs)

Change-Id: I846ad3353dd7d6ef78ec096565e491d7a6eef44a
Signed-off-by: dongsug.song <dongsug.song@samsung.com>