Push: be able to test Push

Create `:libraries:network`

libraries/push/api/src/main/kotlin/io/element/android/libraries/push/api/PushService.kt

@@ -20,4 +20,6 @@ interface PushService {
     fun setCurrentRoom(roomId: String?)
     fun setCurrentThread(threadId: String?)
     fun notificationStyleChanged()
+
+    suspend fun testPush()
 }

libraries/push/api/src/main/kotlin/io/element/android/libraries/push/api/gateway/PushGatewayFailure.kt

@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2023 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.libraries.push.api.gateway
+
+sealed class PushGatewayFailure : Throwable(cause = null) {
+    object PusherRejected : PushGatewayFailure()
+}