Feature request: implement `IdempotencyHandler`

[saragerion]

Use case

All the usages of the Idempotency utility described in #447 share most of their internal logic. This is because in all cases, there are some actions to be taken before and after the function being made idempotent.

For this reason the logic that handles idempotency can be extracted in its own class and reused across all access patterns. This class should be called IdempotencyHandler.

Note that there's already an initial basic implementation of the class under packages/idempotency/src. As a part of this issue, the resolver should revisit this function and align the implementation with the version seen in Powertools for Python.

Solution/User Experience

Users should not use this class directly. The class will be used under the hood by the decorator, Middy middleware, and wrapper function.

Alternative solutions

No response

Acknowledgment

• This feature request meets Lambda Powertools Tenets
• Should this be considered in other Lambda Powertools languages? i.e. Python, Java