feat: increase default and allow changing snackbar auto hide duration

[drodil]

Hey, I just made a Pull Request!

Increase default to 10 seconds as 5 seconds is pretty low to automatically hide the snackbars. Also allow users to configure this as they like.

:heavy_check_mark: Checklist

• [x] A changeset describing the change and affected packages. (more info)
• [ ] Added or updated documentation
• [ ] Tests for new functionality and regression tests for bug fixes
• [ ] Screenshots attached (for UI changes)
• [x] All your commits have a Signed-off-by line in the message. (more info)

[backstage-goalie[bot]]

Changed Packages

Package Name	Package Path	Changeset Bump	Current Version
@backstage/plugin-notifications	plugins/notifications	patch	v0.2.1-next.1

[github-actions[bot]]

Uffizzi Cluster pr-24611 was deleted.

[github-actions[bot]]

Thank you for contributing to Backstage! The changes in this pull request will be part of the 1.27.0 release, scheduled for Tue, 14 May 2024.