Open Radar

 
Summary:
Navigation bar title ignores `navigationBarTitleDisplayMode` when NavigationView shown via `.sheet` and contained in conditional content view.

Steps to reproduce:
1. Create SwiftUI iOS app with following implementation
```
import SwiftUI

@main
struct SheetNavApp: App {
  var body: some Scene {
    WindowGroup {
      ContentView()
    }
  }
}

struct ContentView: View {
  @State var showSheet = false

  var body: some View {
    Button("Show sheet") { showSheet = true }
    .sheet(isPresented: $showSheet) { SheetView() }
  }
}

struct SheetView: View {
  enum ViewState {
    case initial, navigationView
  }
  @State private var state: ViewState = .initial

  @ViewBuilder
  var body: some View {
    switch state {
    case .initial:
      VStack {
        Button("Show navigation") { state = .navigationView }
      }
    case .navigationView:
      NavigationView {
        VStack {
          Text("In navigation")
        }
        .navigationTitle("A title")
        .navigationBarTitleDisplayMode(.inline)
      }
    }
  }
}
```
2. Run app on iOS 15 device
3. Tap on 'Show sheet' button
4. Tap on 'Show navigation' button

Observed behavior:
Navigation bar title displayed in `large` mode.

Expected behavior:
Navigation bar title displayed in `inline` mode

Note:
In iOS 14.5 title displayed correctly.
Also `.navigationBarHidden(true)` modifier does not work in this case as well.