Android: Add Java QtSignalListener interface

This class is being moved from QtDeclarative to QtCore as a part of
API review resutls.

Pick-to: 6.8
Task-number: QTBUG-126976
Task-number: QTBUG-127082
Change-Id: I1c7a20daeb0d398bc6faad441ebae6136b4a88ba
Reviewed-by: Assam Boudjelthia <assam.boudjelthia@qt.io>

src/android/jar/CMakeLists.txt

@@ -50,6 +50,7 @@ set(java_sources
     src/org/qtproject/qt/android/QtAbstractItemModelProxy.java
     src/org/qtproject/qt/android/QtModelIndex.java
     src/org/qtproject/qt/android/QtAbstractListModel.java
+    src/org/qtproject/qt/android/QtSignalListener.java
 )
 
 qt_internal_add_jar(Qt${QtBase_VERSION_MAJOR}Android

src/android/jar/src/org/qtproject/qt/android/QtSignalListener.java

@@ -0,0 +1,17 @@
+// Copyright (C) 2024 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+
+package org.qtproject.qt.android;
+
+/**
+ * A callback that notifies clients when a signal is emitted from the QML component.
+ **/
+@FunctionalInterface
+public interface QtSignalListener<T> {
+    /**
+     * Called on the Android UI thread when the signal has been emitted.
+     * @param signalName literal signal name
+     * @param value the value delivered by the signal or null if the signal is parameterless
+     **/
+    void onSignalEmitted(String signalName, T value);
+}