Feature Request: Linting rules apply only to new changes

[jdolle]

Use case: We need to onboard existing schemas that do not conform to our desired set of linting rules, but want to prevent any new non-compliant schema changes from ending up in our supergraph.

Proposed Solution: We'd like to be able to optionally only run linting against any new changes to a target's schema. The initial push may need to be a force push or as part of this setting, it may ignore the first push of a schema. I'm not too familiar with Hive's codebase yet so I'm not sure if linting runs with compatibility or on push.

It may be nice to somehow show the existing linting errors as well so teams are aware of these issues, but they should not block compatibility/publishing.