Cleanup + Add per user store.

libraries/session-storage/api/src/main/kotlin/io/element/android/libraries/sessionstorage/api/SessionStore.kt

@@ -26,3 +26,7 @@ interface SessionStore {
     suspend fun getLatestSession(): SessionData?
     suspend fun removeSession(sessionId: String)
 }
+
+fun List<SessionData>.toUserList(): List<String> {
+    return map { it.userId }
+}