Update to reflect API changes from beta to final

[helje5]

Lots of them, from ObservableObject to onTapAction.

[helje5]

• TabbedView => TabView
• BindableObject => ObservableObject
• ObjectBinding => ObservedObject
• tapAction => onTapGesture
• what else has changed?

[helje5]

Update to reflect API changes from beta to final

tapAction was renamed to onTapGesture in SwiftUI, that's why:

@available(iOS 13.0, OSX 10.15, watchOS 6.0, *)
@available(tvOS, unavailable)
extension View {
    public func onTapGesture(count: Int = 1, perform action: @escaping () -> Void) -> some View
}