Initial draft of Simple UI (#1499)

A very simple UI based on Vaadin 24.

hawkbit-runtime/hawkbit-simple-ui/src/main/resources/application.properties

@@ -0,0 +1,24 @@
+#
+# Copyright (c) 2023 Contributors to the Eclipse Foundation
+#
+# This program and the accompanying materials are made
+# available under the terms of the Eclipse Public License 2.0
+# which is available at https://www.eclipse.org/legal/epl-2.0/
+#
+# SPDX-License-Identifier: EPL-2.0
+#
+
+server.port=${PORT:8088}
+spring.cloud.openfeign.httpclient.hc5.enabled=true
+
+### Vaadin start ###`
+# build with mvn vaadin:build-frontend to enable / disable
+vaadin.frontend.hotdeploy=false
+logging.level.org.atmosphere = warn
+spring.mustache.check-template-location = false
+# Launch the default browser when starting the application in development mode
+vaadin.launch-browser=true
+# To improve the performance during development.
+# For more information https://vaadin.com/docs/flow/spring/tutorial-spring-configuration.html#special-configuration-parameters
+vaadin.whitelisted-packages = com.vaadin,org.vaadin,dev.hilla,com.eclipse.hawkbit
+### Vaadin end ###