fix: dont add to parent from _setupAsRootView

[farfromrefug]

In some cases you might want to set a parent(mostly rootView) before _setupAsRootView so that the the view calling _setupAsRootView inherits CSS variables and classes from the parent.
This is especially done in plugins like bottomsheet or dialogs or popover.
The issue is that if you set parent before _setupAsRootView then _addViewToNativeVisualTree will be called which could break things like it does with RadSideDrawer nativescript-community/ui-material-components#462.

This PR fixes that by just preventing _addViewToNativeVisualTree to be called from _setupAsRootView which makes sense to me.

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What is the current behavior?

What is the new behavior?

Fixes/Implements/Closes #[Issue Number].