Add simulated refresh interval picker

iOS/Settings/SettingsRefreshSelectionView.swift

@@ -0,0 +1,35 @@
+//
+//  SettingsRefreshSelectionView.swift
+//  NetNewsWire-iOS
+//
+//  Created by Maurice Parker on 9/16/19.
+//  Copyright © 2019 Ranchero Software. All rights reserved.
+//
+
+import SwiftUI
+
+struct SettingsRefreshSelectionView: View {
+
+	@Environment(\.presentationMode) var presentation
+	@Binding var selectedInterval: RefreshInterval
+	
+    var body: some View {
+		Form {
+			ForEach(RefreshInterval.allCases) { interval in
+				Button(action: {
+					self.selectedInterval = interval
+					self.presentation.wrappedValue.dismiss()
+				}) {
+					HStack {
+						Text(interval.description())
+						Spacer()
+						if interval == self.selectedInterval {
+							Image(systemName: "checkmark")
+						}
+					}
+				}.buttonStyle(VibrantButtonStyle(alignment: .leading))
+			}
+		}
+	}
+	
+}