feat(MatSnackBar): Pause dismiss when hovering snackbar

[aapjaapan]

Feature Description

When snackbar has some info that needs more time to process, would be nice that when hovering the snackbar it would not close despite the duration

Use Case

No response

[andrewseguin]

If you have a snackbar that needs time to digest, perhaps adding a dismiss button would be better than expecting users to know about hovering