refactor: two-screen app-list editor with native List layout

Screen 1 is a plain List (name field, the apps the list contains via
FamilyControls token Labels, and an Edit Apps button); screen 2 pushes
Apple's FamilyActivityPicker whose Save applies the selection back.
Documents that the picker silently drops selections without real
FamilyControls authorization (mocked in -ui-testing launches).

OpenAppLockUITests/AppListUITests.swift

@@ -58,6 +58,14 @@ final class AppListUITests: XCTestCase {
         let nameField = app.textFields["appListNameField"].waitToAppear()
         nameField.tap()
         nameField.typeText("Focus Apps\n")
+
+        // Screen 1 lists the (empty) selection; Edit Apps pushes the Screen
+        // Time picker, whose Save returns here.
+        app.element("emptySelectionLabel").waitToAppear()
+        app.buttons["editAppsButton"].tap()
+        app.element("selectionCountLabel").waitToAppear()
+        app.buttons["confirmSelectionButton"].tap()
+
         app.buttons["saveAppListButton"].waitToAppear().tap()
 
         // Saving pops back to the picker with the new list selected.