feat(commons): update types to have optional callback

[flochaz]

Description of your changes

Following discussions made here: DefinitelyTyped/DefinitelyTyped#38342 (comment) and the proposed solution made here: https://www.npmjs.com/package/aws-lambda-consumer , this PR enable to specify lambda handlers with or without callback depending on if it's a sync or async call.

How to verify this change

cd packages/commons
npm run test

Also tested against Metrics decorator . PR will follw

Related issues, RFCs

#381

PR status

Is this ready for review?: YES
Is it a breaking change?: NO

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
• The code coverage hasn't decreased
• I have added tests that prove my change is effective and works
• New and existing unit tests pass locally and in Github Actions
• Any dependent changes have been merged and published in downstream module
• The PR title follows the conventional commit semantics

Breaking change checklist

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

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