feat(instrumentation-aws-lambda): take care of ESM based (.mjs) handlers

[serkan-ozal]

Which problem is this PR solving?

Currently, ESM based handlers with .mjs file extension are not taken care of by AWS Lambda instrumentation, but ESM based handlers are supported since long time (https://aws.amazon.com/tr/about-aws/whats-new/2022/01/aws-lambda-es-modules-top-level-await-node-js-14/).

Short description of the changes

For the fix, while handler file is being resolved, in addition to .js and .cjs file extensions, .mjs file extension is also checked.

This PR is the contrib counter part of the open-telemetry/opentelemetry-js#5094

[codecov]

Codecov Report

Attention: Patch coverage is 42.85714% with 4 lines in your changes missing coverage. Please review.

Project coverage is 90.56%. Comparing base (9a20e15) to head (118eb8e).

Files with missing lines	Patch %	Lines
...-instrumentation-aws-lambda/src/instrumentation.ts	42.85%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2508      +/-   ##
==========================================
- Coverage   90.85%   90.56%   -0.29%     
==========================================
  Files         159      154       -5     
  Lines        7853     7548     -305     
  Branches     1622     1581      -41     
==========================================
- Hits         7135     6836     -299     
+ Misses        718      712       -6     

Files with missing lines	Coverage Δ
...-instrumentation-aws-lambda/src/instrumentation.ts	93.29% <42.85%> (-1.92%)	⬇️

... and 6 files with indirect coverage changes

[raphael-theriault-swi]

Looks like a subset of #2000, thanks for addressing the issue in the instrumentation code wrt. absolute paths !