try to test MatBlazor + IMatDialogService

[drma-tech]

SamProf/MatBlazor#919

I know this is a matter exclusively for MatBlazor or I'm a bit stuck and not knowing how to correctly initialize the service.

But as you guys may have already tested several third-party components, you may have already gone through this situation.

I don't know if it's really a matter of correctly initializing the service or a matter of correctly passing the CascadingParameter

[drma-tech]

<MatPortalHost></MatPortalHost>

maybe it has something to do with it, but I'm not sure how to enable it in BUnit.