Parse/expose publiccode.yml and codemeta.json data

[codemeta.json](https://github.com/codemeta/codemeta) and [publiccode.yml](https://github.com/publiccodeyml/publiccode.yml) are used to describe software projects.

Some public sector projects are using publiccode.yml, such as [demarches-simplifiees](https://github.com/demarches-simplifiees/demarches-simplifiees.fr/blob/main/publiccode.yml). codemeta.json seems more used for research projects.

Some of the data in these files are declarative, parsing/exposing them would be a real plus when it comes to knowing the projects behind the repositories, e.g. in terms of maintainance.

Is it something that would be relevant for ecosyste.ms?

Cc'ing @hjonin as we've discussing this in the past.

The issue names publiccode.yml and codemeta.json but no repository files, tests, or entry points. Start by comparing the two metadata specifications and reviewing the existing summary API behavior; clarify which fields should be parsed and exposed. Done requires an agreed scope and corresponding API behavior.

Written by the indexing model from the issue text.