[NUI] introduce CreateViewStyle that is alternative to GetViewStyle (#1681)

[NUI] introduce CreateViewStyle that is alternative to GetViewStyle (#1681)

`CreateViewStyle` is alternative method of `GetViewStyle`.
To resolve CA1721, please use `CreateViewStyle` instead.
```
warning CA1721: The property name 'ViewStyle' is confusing given the existence of
method 'GetViewStyle'. Rename or remove one of these members.
```

`GetViewStyle` should be deprecated(or removed) if there is no
compatibility issue.