Move SessionGraphFactory back to the appnav module

The share feature does not need it anymore, so there is no reason to expose it
in the matrix api module.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/SessionGraphFactory.kt

@@ -1,17 +0,0 @@
-/*
- * Copyright (c) 2025 Element Creations Ltd.
- * Copyright 2023-2025 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.matrix.api
-
-/**
- * Create the dependency injection graph of a session.
- * It can be used to get session scoped dependencies of a session which is not the current one.
- */
-interface SessionGraphFactory {
-    fun create(client: MatrixClient): Any
-}