Make sure to save the tokens the Client might return when its session is restored (#3378)

* Use `ClientSessionDelegate` to ensure tokens are always updated.

Refreshed tokens on client restoration might not have been stored to disk if the token refresh happened before `RustMatrixClient` was built and the `ClientDelegate` was set in it.

Using `ClientSessionDelegate` should ensure the tokens refreshed callback is called at any point in time.

* Improve how assigning the Client works, fix docs

* Fix review comments

libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/FakeMatrixClient.kt

@@ -122,7 +122,7 @@ class FakeMatrixClient(
     var getRoomInfoFlowLambda = { _: RoomId ->
         flowOf<Optional<MatrixRoomInfo>>(Optional.empty())
     }
-    var logoutLambda: (Boolean) -> String? = {
+    var logoutLambda: (Boolean, Boolean) -> String? = { _, _ ->
         null
     }
 
@@ -170,8 +170,8 @@ class FakeMatrixClient(
         clearCacheLambda()
     }
 
-    override suspend fun logout(ignoreSdkError: Boolean): String? = simulateLongTask {
-        return logoutLambda(ignoreSdkError)
+    override suspend fun logout(userInitiated: Boolean, ignoreSdkError: Boolean): String? = simulateLongTask {
+        return logoutLambda(ignoreSdkError, userInitiated)
     }
 
     override fun close() = Unit