Report the use of experimental features in the SBOM

[brunoapimentel]

In Cachi2, experimental features are opt-in and are not ready for use in production. To further help users understand this, and to provide means for other tools that consume the produced SBOM to take action based on this information, we need to add an extra field to the SBOM stating that it experimental features were used while producing it.

Some suggestions for the CycloneDX SBOM:

.metadata.properties[] = {"cachi2:experimental_features": "true"}
.components[].properties[] = {"cachi2:found_by:experimental": "true"}