Return cached room members before fetching new ones, do it in batches (#2274)

* Use cached users from the Rust SDK.

Also lazy load received users by batches.

* Create `RoomMemberListFetcher` to wrap all the room member loading logic

* Ensure we clear `RoomMember` Rust references if the fetching coroutine is canceled

tests/testutils/src/main/kotlin/io/element/android/tests/testutils/WithFakeLifecycleOwner.kt

@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2024 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.tests.testutils
+
+import android.annotation.SuppressLint
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.CompositionLocalProvider
+import androidx.compose.runtime.Stable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.platform.LocalLifecycleOwner
+import androidx.lifecycle.Lifecycle
+import androidx.lifecycle.LifecycleOwner
+import androidx.lifecycle.LifecycleRegistry
+
+@Stable
+@Composable
+fun <T> withFakeLifecycleOwner(lifecycleOwner: FakeLifecycleOwner = FakeLifecycleOwner(), block: @Composable () -> T): T {
+    var state: T? by remember { mutableStateOf(null) }
+    CompositionLocalProvider(LocalLifecycleOwner provides lifecycleOwner) {
+        state = block()
+    }
+    return state!!
+}
+
+@SuppressLint("VisibleForTests")
+class FakeLifecycleOwner : LifecycleOwner {
+    override val lifecycle: Lifecycle = LifecycleRegistry.createUnsafe(this)
+
+    fun givenState(state: Lifecycle.State) {
+        (lifecycle as LifecycleRegistry).currentState = state
+    }
+}