feat(commons): centralize cold start heuristic

[dreamorosi]

Description of your changes

This PR introduces a new Utility class in the @aws-lambda-powertools/commons package. This class is designed to be extended by other Powertools utilities that will inherit its shared methods.

In this iteration the Utility class brings a centralised cold start heuristic to be shared by all core packages.

The changes in this PR have already been discussed in an internal RFC document reviewed by at least two other maintainers as per CONTRIBUTING guidelines.

How to verify this change

Clone the repo & check newly introduced unit tests.
Also check the JSDoc documentation written in the class file.

Related issues, RFCs

#484

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
• The PR title follows the conventional commit semantics

Breaking change checklist

N/A

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[ijemmy]

Only typo and grammar. This rest looks good.

[saragerion]

What would be the use case of testing the functionality from a child class?

[dreamorosi]

The other utilities (Tracer, Logger, etc.) will extend this Utility class and use it just like in this test case. I agree that it might be a little redundant but adding one test case was easier/faster than build+pack the new version of commons & install it in another package to test it.

[saragerion]

LGTM!