Return unique include and revInclude resources per search filter match.

[aditya-07]

IMPORTANT: All PRs must be linked to an issue (except for extremely trivial and straightforward changes).

Fixes #2512

Description

1. Return distinct included and revIncluded resource per searchIndex.
2. When user updates a resource, if the resource has an meta.lastUpdated, use that for index value.

Alternative(s) considered Have you considered any alternatives? And if so, why have you chosen the approach in this PR?

Type Choose one: Bug fix Screenshots (if applicable)

Checklist

• [ ] I have read and acknowledged the Code of conduct.
• [ ] I have read the Contributing page.
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• [ ] I have discussed my proposed solution with code owners in the linked issue(s) and we have agreed upon the general approach.
• [ ] I have run ./gradlew spotlessApply and ./gradlew spotlessCheck to check my code follows the style guide of this project.
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• [ ] I have built and run the demo app(s) to verify my change fixes the issue and/or does not break the demo app(s).