Run efsity validation against the fhir-resources repo via github actions

[pld]

1. [ ] pull the jar straight from this repo, or put it up on mvn
2. [ ] run validation against the root directory for every PR

That's it! Some things we may have to do depending on what happens with the above:

1. change the output, or add an option to change the output, so it's easier to interpret by the github action as pass/failed

[Wambere]

Linked to https://github.com/onaio/fhir-resources/discussions/1363

I think it makes sense to break this down to 3 steps:

1. Automatically validate FHIR resources pushed to the FHIR resources repo with Github actions
2. Automatically POST validated resources to the FHIR server backend
3. Integrate implementation Guides/Profiles to customize resource validation

For the first point, the plan so far is to:

• Create a new Github actions workflow triggered by a push or pull request to the fhir-resources repo
• Setup working environment
• Checkout PR branch (with changes)
• Download latest efsity jar as an artifact directly from the fhircore-tooling repo
• Run validation command (maybe from a script? this way we can keep changing the script and not the action/jobs) on the files changed in the PR

cc @ndegwamartin @pld

[ndegwamartin]

The integration for No. 2 above could borrow from standalone implementation documented in #29