Change user setup prompt dialog showing logic

- Extract user setup prompt dialog creation logic
- Move user setup prompt dialog showing to UserDetailsSettings
- Rename user click and creation related methods to improve readability
- Set "disabled by admin" for switch pref when switch is disabled
- Cleanup UserSettings and UserDetailsSettings onPreferenceClick
- After a guest is created the details page opens instead of switching

Test: Manual test and robo tests with this command:
  make -j64 RunSettingsRoboTests
Demo: http://shortn/_ACYsnbIKO9
Bug: 156867277
Change-Id: Ifa0cdefcd49d5b865e940a7cc332136ed26ecf57

src/com/android/settings/users/UserDialogs.java

@@ -138,4 +138,21 @@ public final class UserDialogs {
                 .setNegativeButton(android.R.string.cancel, null)
                 .create();
     }
+
+    /**
+     * Creates a dialog to confirm that the user is ok to start setting up a new user.
+     *
+     * @param onConfirmListener Callback object for positive action
+     */
+    public static Dialog createSetupUserDialog(Context context,
+            DialogInterface.OnClickListener onConfirmListener) {
+        return new AlertDialog.Builder(context)
+                .setTitle(com.android.settingslib.R.string.user_setup_dialog_title)
+                .setMessage(com.android.settingslib.R.string.user_setup_dialog_message)
+                .setPositiveButton(com.android.settingslib.R.string.user_setup_button_setup_now,
+                        onConfirmListener)
+                .setNegativeButton(com.android.settingslib.R.string.user_setup_button_setup_later,
+                        null)
+                .create();
+    }
 }