rover supergraph: query latest composition errors

[lrlna]

Description

Providing we are not able to successfully run rover supergraph fetch, this feature should allow to get a few of the latest composition errors from the registry in a local environment. This was brought up in #485.

Things to think about:

• what should this command look like?
• does this API endpoint already exist, or does the registry need to be built?
• does studio already show these, and should we try to echo a similar output to the studio?

[EverlastingBugstopper]

what should this command look like?

idk... maybe like rover supergraph fetch --latest or something? not sure on this one. it's a bit of a different paradigm than the rest of our commands

does this API endpoint already exist, or does the registry need to be built?

it is already built, and we fetch it already as part of the work on #485

does studio already show these, and should we try to echo a similar output to the studio?

yeah, you can get there by clicking on a federated graph, and then up at the top there's a federated button with a red X on it if composition is broken. It looks pretty much exactly how the rest of our composition errors look

[abernix]

See related #113