add NSE sources to EX project to easily implement mocking and allow the code to be unit tested

ElementX/Sources/Mocks/NSEUserSessionMock.swift

@@ -0,0 +1,24 @@
+//
+// Copyright 2025 Element Creations Ltd.
+//
+// SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+// Please see LICENSE files in the repository root for full details.
+//
+
+import MatrixRustSDK
+
+struct NSEUserSessionMockConfiguration {
+    var inviteAvatarsVisibility = InviteAvatars.on
+    var mediaPreviewVisibility = MediaPreviews.on
+    var threadsEnabled = true
+}
+
+extension NSEUserSessionMock {
+    convenience init(_ configuration: NSEUserSessionMockConfiguration) {
+        self.init()
+        
+        underlyingInviteAvatarsVisibility = configuration.inviteAvatarsVisibility
+        underlyingMediaPreviewVisibility = configuration.mediaPreviewVisibility
+        underlyingThreadsEnabled = configuration.threadsEnabled
+    }
+}