Sample Compose App For A Custom CI Pipeline

This is a sample compose App is used for an example of a custom CI pipeline integration with a FoundriesFactory.

In particular, it provides guidance to accomplish the following in a scope of a github actions workflow:

• building multi-arch container images and pushing them to Foundries Registry;
• building Foundries Compose App and pushing it to Foundries Registry;
• composing TUF Target role metadata compliant with FoundriesFactory TUF requirements;
• adding the composed TUF Targets to FoundriesFactory's Targets.