[Snackbar] Add bottom button positioning

[JeremiasUX]

We received a request for this feature:

• Slack: https://adevinta.slack.com/archives/C059UCP6B63/p1713511075397319
• Spark form: https://docs.google.com/spreadsheets/d/1xDti05i5kp7vwUkCtA-EbLtU0BKZWcZmGpZHvI-Rqqg/edit#gid=1951364618

Requested by: Cindy Deadline: Second half of Q2 Platform: iOS (UiKit and Swift) and Android Component: Snackbar

What has been requested:

• The team would need to have the button below the content of the snackbar
• On android this is a default behavior https://m3.material.io/components/snackbar/specs#645d590c-af7f-4d7c-8e02-4c755043fa7d

Design - Decision:

• The design team has agreed that this is a valid reason to add this missing feature
• Design team will also push for Snackbar guidelines to make sure the usage is correct

Next steps:

• [x] Update Spec sheet
• [ ] Update ZeroHeight
• [x] Update Figma
• [ ] Handover to spark developers
• [ ] Communicate changes