[NUI] Add constructor with style instance

[NUI] Add constructor with style instance

To customize and apply app's own style instance, constructor with style
instance should be added.

For now, ApplyStyle() modifies the given properties only based on the
default style unlike applying style in constructor.
e.g. Let default style contain properties A, B, C.
     Let custom style contain properties B, C.
     Then ApplyStyle(custom style) contain default style's A and custom
     style's B and C.

Consequently, to apply custom style without applying default style,
constructor with style instance is required.