Introduce Signal API and SYNC-DURABLE consisteny during execution

[shaileshpadave]

Pull Request type

• [ ] Bugfix
• [X] Feature
• [ ] Refactoring (no functional changes, no api changes)
• [ ] Build related changes
• [ ] WHOSUSING.md
• [ ] Other (please describe):

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Changes in this PR

• Introduce Signal API and SYNC-DURABLE consisteny during execution

Describe the new behavior from this PR, and why it's needed Issue #

Alternatives considered

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