[Feature request] Include @requires usage of subgraph fields for insights

Not sure on what the consequences of this would be, but a thing i've been wondering at times is how often certain fields get fetched through `@requires` by other subgraphs. In essence this is not so different as a client interacting with the federated gateway and fetching data. In other words defining an `@requires` on a field is in essence just a client fetching data from that subgraph.

A situation where this could prove useful is when in hive insights the usage is none by outside clients but the field are still being used through `@requires`. Currently you're rather blind on the amount of traffic going to that subgraph. It can even give you the impression that the field can be cleaned up. even though its still `@externally` referenced.

Curious in your thoughts and implications of this !