Replace our firstIfSingle extension with singleOrNull from the Kotlin library.

libraries/core/src/main/kotlin/io/element/android/libraries/core/extensions/List.kt

@@ -1,15 +0,0 @@
-/*
- * Copyright 2024 New Vector Ltd.
- *
- * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
- * Please see LICENSE files in the repository root for full details.
- */
-
-package io.element.android.libraries.core.extensions
-
-/**
- * Returns the first element if the list contains exactly one element, otherwise returns null.
- */
-inline fun <reified T> List<T>.firstIfSingle(): T? {
-    return if (size == 1) first() else null
-}