feat(seedless-onboarding-controller): add soft delete APIs for secret data items

[huggingbot]

Explanation

This PR adds support for soft deleting secret data items from the metadata store

Add two new methods to SeedlessOnboardingController:

• deleteSecretDataItem({ itemId }) - Soft deletes a single item
• batchDeleteSecretDataItems({ itemIds }) - Soft deletes multiple items

References

Related to https://consensyssoftware.atlassian.net/browse/SL-341

Checklist

• [x] I've updated the test suite for new or updated code as appropriate
• [x] I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• [x] I've communicated my changes to consumers by updating changelogs for packages I've changed
• [x] I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them