Description of your changes

This PR switches some of the integration tests to use the ESM builds of the Powertools for AWS Lambda utilities so that we can increase confidence in these builds.

To achieve this I made the following changes:

• modified the TestNodejsFunction construct to use either CJS or ESM based on inputs
• switched ~50% of the functions in the e2e to use ESM
• added a new test case for the Lambda Layers test to include ESM (with corresponding refactor)*

While at it, I also enabled minification and some other small bundle optimizations for the functions in our e2e tests.

• This is true, excluding Node.js 16 for which I maintained only the CJS tests for the Layer. This is due to this and I also added a sentence in the docs to call out this limitation for Node.js 16, Layer, and ESM.

Related issues, RFCs

Issue number: #2346

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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