Introduce GraphQL::Schema::Visibility with Subset and Migration classes

Introduce GraphQL::Schema::Visibility with Subset and Migration classes: a task in bird-critic-1.5-full-300 (Harbor dataset). graphql-ruby is a pure Ruby gem providing GraphQL execution. This task replaces the earlier GraphQL::Schema::Subset experiment with a more complete visibility system…

The task

graphql-ruby is a pure Ruby gem providing GraphQL execution. This task replaces the earlier `GraphQL::Schema::Subset` experiment with a more complete visibility system: `GraphQL::Schema::Visibility`. The new system is activated via `use GraphQL::Schema::Visibility` on a schema class, which installs…

Part of kochsnow/bird-critic-1.5-full-300.