feature request: Laboratory shows from which subgraph is resolved each field

[yanns]

Feature requets

In laboratory, for a given GraphQL query, it'd be great if it'd be possible to show for each field which subgraph will resolve it.

[kamilkisiela]

Different gateways may produce different query plans. We can't assume all users are using gateway X.
That's why showing an exact subgraph that will resolve a field is impossible (it will work only in cases where a field belongs to a single subgraph).

The only info we can show that is true for all the gateways is a list of subgraphs that are able to resolve a field.