Create execution testing pipeline

[dotasek]

This adds a job template that runs the build ig-publisher on specific IGs.

The intent of this is to ensure several things:

1. That included dependencies are correctly included in the jar (as unit tests and the jar may have different dependencies).
2. That tool execution (such as jekyll, git, and fsh-sushi) are interacting correctly with the executable jar.
3. That example IGs complete without runtime errors.

The IGs currently chosen are:

• fhir-tools-ig
• ACME-FSH-IG-Example

[dotasek]

Merging following conversation with @grahamegrieve on Zulip.