test(ssm): add test for cross-account shared SSM parameters not working

[iiroj]

This Draft PR demonstrates a failure scenario in the @middy/ssm middleware where cross-account shared paramaters are not working correctly, as stated in https://github.com/middyjs/middy/issues/1529

Todo List:

• [ ] All commits are cryptographically signed
• [ ] Feature/Fix fully implemented
• [ ] Updated relevant types
• [x] Added tests (if applicable)
  • [x] Unit tests
  • [ ] Fuzz tests
  • [ ] Type tests
  • [ ] Benchmark tests
• [ ] Updated relevant documentation
• [ ] Updated relevant examples

[iiroj]

I also took the liberty of introducing one way to hopefully fix the issue. It's probably not the most optimal solution, though!

[willfarrell]

Hey, thanks for putting this together! I’m at AWS re:Invent right now and won’t be able to look into this till I’m back home in a week or so.