fix(idempotency): skip persistence for optional idempotency key

[am29d]

Description of your changes

I have implemented a skip step within IdempotencyHandler instead of BasePersistenceLayer. The reason for that was to skip the flow as early as possible and avoid any additional overhead on IdempotencyRecord computation. The downside is now the same functionality needs to be ported to the middy implementation, because it does not reuse the IdempotencyHandler logic.

I am don't like the solution, though it solve the problem for now. I think we should refactor the IdempotencyHandler to suite the middy implementation and have one control flow. Open to any suggestion, if there is another way to handle that. The skip step feels like an additional middleware step we can attach to the idempotency, but I lack deeper middy knowledge how we could chain it transparently.

Related issues, RFCs

Issue number: #1501

Checklist

• My changes meet the tenets criteria
• I have performed a self-review of my own code
• I have commented my code where necessary, particularly in areas that should be flagged with a TODO, or hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my change is effective and works
• The PR title follows the conventional commit semantics

Breaking change checklist

Is it a breaking change?: NO

• I have documented the migration process
• I have added, implemented necessary warnings (if it can live side by side)

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