Move cache management to a dedicated class and in the setting module, for clarity.

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

@@ -29,13 +29,6 @@ interface MatrixAuthenticationService {
     suspend fun setHomeserver(homeserver: String): Result<Unit>
     suspend fun login(username: String, password: String): Result<SessionId>
 
-    /*
-     * Cache index
-     */
-
-    fun cacheIndex(): Flow<Int>
-    fun incrementCacheIndex()
-
     /*
      * OIDC part.
      */