feat(idempotency): implement IdempotencyHandler

[am29d]

This is a small PR for the #1303 implementation. Most of the IdempotencyHandler was already implemented and aligned with decorator and function wrapper. In addition, I have added a try mechanism to mitigate rare race conditions error, similar to python implementation.

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Related issues, RFCs

Issue number: closes #1303

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• My changes meet the tenets criteria
• I have performed a self-review of my own code
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Is it a breaking change?: NO

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[dreamorosi]

Looking good, I just would like to address one return type and remove a ts-ignore before merging

[dreamorosi]

Before we merge, can we fix this return type and remove the comment?

Based on what I see, we either need to change the return type to Promise<U | undefined> or make sure that the function returns something in the catch block when the if statement is skipped.

[am29d]

Hmm this is weird construct we have there. Adding undefined to the Promise would leak it further to makeIdempotentFunction and also higher to the user api, which I'd like to avoid. TS complains about missing return statement outside of the for-loop. But adding a statement makes it impossible to test, because this return statement is unreachable. I have added a throw with coverage ignore.