Fixed accessibility issues in Wi-Fi SSID view for SUW

- Keep the Save button enabled at all times

- Show "Enter the SSID" to remind the user

Bug: 386897596
Flag: EXEMPT bugfix
Test: Manual testing
  atest WifiDialogActivityTest \
        WifiConfigControllerTest
Change-Id: I577e78c34cbaa0640479adf09a916a526500fe68

src/com/android/settings/wifi/WifiDialogActivity.java

@@ -346,6 +346,9 @@ public class WifiDialogActivity extends ObservableActivity implements WifiDialog
     @Override
     public void onDismiss(DialogInterface dialogInterface) {
         mDialog2 = null;
+        if (mDialog != null && mDialog.shouldSubmitBeforeFinish()) {
+            onSubmit(mDialog);
+        }
         mDialog = null;
         finish();
     }