fix:dismiss server url view on entering correct url

app/src/main/java/chat/rocket/android/fragment/add_server/InputHostnameContract.java

@@ -7,7 +7,7 @@ public interface InputHostnameContract {
   interface View extends BaseContract.View {
     void showLoader();
 
-    void hideLoader();
+    void hideLoader(Boolean isValidServerUrl);
 
     void showInvalidServerError();
 

app/src/main/java/chat/rocket/android/fragment/add_server/InputHostnameFragment.java

@@ -97,9 +97,11 @@ public class InputHostnameFragment extends AbstractFragment implements InputHost
     }
 
     @Override
-    public void hideLoader() {
-        waitingView.setVisibility(View.GONE);
-        container.setVisibility(View.VISIBLE);
+    public void hideLoader(Boolean isValidServerUrl) {
+        if(!isValidServerUrl) {
+            waitingView.setVisibility(View.GONE);
+            container.setVisibility(View.VISIBLE);
+        }
     }
 
     @Override

app/src/main/java/chat/rocket/android/fragment/add_server/InputHostnamePresenter.java

@@ -16,6 +16,7 @@ import io.reactivex.disposables.Disposable;
 public class InputHostnamePresenter extends BasePresenter<InputHostnameContract.View> implements InputHostnameContract.Presenter {
   private final RocketChatCache rocketChatCache;
   private final ConnectivityManagerApi connectivityManager;
+  private boolean isValidServerUrl=false;
 
   public InputHostnamePresenter(RocketChatCache rocketChatCache, ConnectivityManagerApi connectivityManager) {
     this.rocketChatCache = rocketChatCache;
@@ -37,10 +38,11 @@ public class InputHostnamePresenter extends BasePresenter<InputHostnameContract.
     final Disposable subscription = ServerPolicyHelper.isApiVersionValid(validationHelper)
         .subscribeOn(AndroidSchedulers.from(BackgroundLooper.get()))
         .observeOn(AndroidSchedulers.mainThread())
-        .doOnTerminate(() -> view.hideLoader())
+        .doOnTerminate(() -> view.hideLoader(isValidServerUrl))
         .subscribe(
             serverValidation -> {
               if (serverValidation.isValid()) {
+                isValidServerUrl=true;
                 onServerValid(hostname, serverValidation.usesSecureConnection());
               } else {
                 view.showInvalidServerError();