Add Attestation Test similar to Examples Repo

With confidential-aci-testing we can now add tests similar to what we have in confidential-aci-examples with minimal code in this repo.

Added the attestation test as a proof of concept, can merge without the others and they can be added later

Todo:

[x] Add a GitHub actions workflow
[x] Make sure it works in fresh environment particularly in a codespaces testing view
[x] ~Find an MCR python image which works~ For future PR's
[x] Understand Analyse workflow failures and fix

microsoft / confidential-sidecar-containers