Various UI test fixes (#370)

* Increase integration tests time limits again as they're still ocasionally failing

* Fixed NavigationRootCoordinator name in logs

* Refactor UI tests hierarchy and introduce new userFlowScreen

* Introduce a RoomTimelineControllerFactory so that it can be mocked in the UserFlow UI tests

* Start using a mock timeline controller for the UserSession flows

* Remove the WeakDictionary dependency and replce it with a plain NSMapTable in the BackgroundTaskService

* Allow multiple UITests screenshots per screen

* Prevent the view hierarchy changing when taking screenshots

* Add UserSessionScreen UI tests

* Fix label triaging workflow project identifier as per vector-im/element-ios/pull/7150

* Fix settings screen tests

* Fix roomPlainNoAvatar and roomEncryptedWithAvatar UI tests

* Fix modal server selection screen UI tests

* Fix bug report and login screen UI tests

* Fix text typing missing characters on UI tests

* Fix sliding sync configuration on integration tests

* Stop crashing if not finding a particular room through the MockClientProxy

UITests/Sources/Application.swift

@@ -41,10 +41,15 @@ extension XCUIApplication {
 
     /// Assert screenshot for a screen with the given identifier. Does not fail if a screenshot is newly created.
     /// - Parameter identifier: Identifier of the UI test screen
-    func assertScreenshot(_ identifier: UITestScreenIdentifier) {
-        let failure = verifySnapshot(matching: screenshot().image,
+    func assertScreenshot(_ identifier: UITestScreenIdentifier, step: Int? = nil) {
+        var snapshotName = identifier.rawValue
+        if let step {
+            snapshotName += "-\(step)"
+        }
+
+        let failure = verifySnapshot(matching: XCUIScreen.main.screenshot().image,
                                      as: .image(precision: 0.99, perceptualPrecision: 0.98, scale: nil),
-                                     named: identifier.rawValue,
+                                     named: snapshotName,
                                      testName: testName)
 
         if let failure,