Implement showsVerticalScrollIndicator property for ScrollView for fabric

[jonthysell]

Implement the showsVerticalScrollIndicator property for the fabric implementation of ScrollView.

This property was available in RNW Paper via ScrollViewManager.

See https://reactnative.dev/docs/scrollview#showsverticalscrollindicator for details.

[Yajur-Grover]

From the paper implementation, this looks like a potential good first issue, as you simply call VerticalScrollBarVisibility() to update whether the vertical scrollbar is shown or hidden. This would likely be implemented in the the ScrollViewComponentView file, and manipulating the m_verticalScrollbarComponent: vnext\Microsoft.ReactNative\Fabric\Composition\ScrollViewComponentView.cpp