Description of your changes

Following the discussion in the linked issue (#1068), as well as other issues (#1080, #1081), customers who are using Powertools and bundling their TypeScript project with tsc, but that were not using any of the Middy-compatible middleware were having compile issues due to the dependency being missing.

We have investigated several workarounds:

• Adding the @middy/core dependency (fix(middleware): add @middy/core as dependency #1218)
• Changing the exports to isolate the middleware & thus the dependency (#1068#issuecomment-1377575328)
• Reworking the types (this PR)

The first option was a no-go as it would have introduced an unnecessary dependency for those users having the issue. The second one would have constituted a breaking change, requiring a major release.

The last option (credits to @saragerion for proposing it) allows us to maintain backwards compatibility while solving the issue described above.

The solution that this PR proposes (again, credits to @saragerion), introduces some of the types previously imported from @middy/core into @aws-lambda-powertools/commons. By bringing these types into the project, we can remove the dependency to @middy/core from our codebase and allow customers to bundle using tsc as well as esbuild.

Note
The @middy/core dependency was used only for its types. Powertools still supports Middy middleware, and customers who want to use them still need to opt-in by adding the dependency to their Lambda functions.

How to verify this change

See existing unit tests below this PR and successful integration test run: https://github.com/awslabs/aws-lambda-powertools-typescript/actions/runs/3894429621

Related issues, RFCs

Issue number: #1068

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
• I have made corresponding changes to the examples
• 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
• 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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