Move Deck exception classes into own files

https://github.com/stefan-niedermann/nextcloud-deck/issues/208

src/main/java/com/nextcloud/client/integration/AppCannotHandelNotificationException.java

@@ -0,0 +1,4 @@
+package com.nextcloud.client.integration;
+
+public class AppCannotHandelNotificationException extends Exception {
+}

src/main/java/com/nextcloud/client/integration/AppNotInstalledException.java

@@ -0,0 +1,4 @@
+package com.nextcloud.client.integration;
+
+public class AppNotInstalledException extends Exception {
+}

src/main/java/com/nextcloud/client/integration/NotificationHandler.java

@@ -12,10 +12,4 @@ public interface NotificationHandler {
     @NonNull
     Intent handleNotification(@NonNull final Notification notification,
                               @NonNull final User user) throws AppNotInstalledException, AppCannotHandelNotificationException;
-
-    class AppNotInstalledException extends Exception {
-    }
-
-    class AppCannotHandelNotificationException extends Exception {
-    }
 }

src/main/java/com/nextcloud/client/integration/deck/DeckNotificationHandler.java

@@ -5,6 +5,8 @@ import android.content.Intent;
 import android.util.Log;
 
 import com.nextcloud.client.account.User;
+import com.nextcloud.client.integration.AppCannotHandelNotificationException;
+import com.nextcloud.client.integration.AppNotInstalledException;
 import com.nextcloud.client.integration.NotificationHandler;
 import com.owncloud.android.lib.resources.notifications.models.Notification;