Engineering discovery: data model for dependencies information

Why is this change being made?

This is the outcome of gitlab-org/gitlab#297661 (closed).

Quotes from the issue description:

I would like for us to think about what data is needed in the longer term to deliver to customers the features they are asking for. Then pick one piece of that data, and keeping in mind the longer term goals, design and do a POC to add some of the data that would give us one or more of the customer features listed below (also feel free to add features!)

A short term proposal for additional data to be stored and a longer term list of data that we would need to have in order to be able to accomplish all the features we currently would like to implement.

Author Checklist

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