docs(idempotency): bring your own persistent store

[dreamorosi]

Description of your changes

This PR introduces a new section to the docs that discusses how to build your own Persistence Layer for the Idempotency utility.

The section follows closely the structure of the same section found in the Python docs but instead it shows how to implement the alternative persistence layer with a generic key-value store.

The PR also:

• extracts all the JSON events and infra snippets (i.e. SAM, Terraform, etc.) to their own dedicated files so that they can be linted/formatted
• adds a missing CDK sample to show how to create the table required for Idempotency

Related issues, RFCs

Issue number: #1484

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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[am29d]

Looks great, just a small change for the CDK example.

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
1 Code Smell

No Coverage information
6.1% Duplication

[dreamorosi]

Comments addressed, merging so I can unblock another PR and avoid merge conflicts on package-lock.json.