Expose whiteboard destroy and persist APIs

[weeman1337]

Required for save-on-leave feature

:heavy_check_mark: Checklist

• [ ] 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 or videos attached (for UI changes).
• [ ] All your commits have a Signed-off-by line in the message (more info).

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: 00a1aa7a087d9ca7505dfa8d79384abbc76168ec

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

| Name | Type | | ---------------------------------- | ----- | | @nordeck/matrix-neoboard-react-sdk | Minor | | @nordeck/matrix-neoboard-widget | Patch |

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