chore: add middy like interfaces to commons package

[dreamorosi]

Description of your changes

This PR is a pre-requisite to be able to start working on issue #373 and it proposes to add two interfaces and one type that mirror the ones defined in @middy/core here.

Before going on and adding our own interfaces in @aws-lambda-powertools/commons I have attempted to search for existing ones in the npm registry and in the DefinitelyTyped repo but found none.

How to verify this change

Check out this branch, run npm pack in packages/commons and try to import MiddyLikeMiddlewareObj or MiddyLikeRequest in your code after installing the tar archive.

Related issues, RFCs

#373

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
• My changes generate no new warnings
• New and existing unit tests pass locally and in Github Actions
• The PR title follows the conventional commit semantics

Breaking change checklist

N/A

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[flochaz]

should we add a simple test to check that export are working as expected, like done for LambdaInterface https://github.com/awslabs/aws-lambda-powertools-typescript/blob/main/packages/commons/tests/unit/LambdaInterface.test.ts ?

[dreamorosi]

should we add a simple test to check that export are working as expected, like done for LambdaInterface https://github.com/awslabs/aws-lambda-powertools-typescript/blob/main/packages/commons/tests/unit/LambdaInterface.test.ts ?

You were right, while adding the tests I realised they weren't exported properly. Good catch!

[dreamorosi]

Closing this PR as it's unnecessary. After talking with @saragerion she pointed out (correctly) that just moving middy as devDependency and changing the imports to import type middy from "@middy/core" already allows us to use the types in our middleware and removes @middy/core itself form the package once you run npm pack.

I've tested this on a local branch and it works, will open a PR for it in the coming days.