Keep overlay position after a resized dialog is opened again

[DiegoCardoso]

With vaadin/vaadin-dialog-flow#153, a dialog can be defined as resizable with dialog.setResizable(true).

Any resize to the overlay is synced so, if a resized dialog is closed and opened again, the size is preserved. But, the overlay position, on the other hand, is not preserved, which can bring a confusing behavior, as a resized dialog will be reopened aligned to the center of the page and not to its last position before being closed.

See the example below: