Easier way to create a type instance dynamically

[p-bakker]

Feature description

When dynamically adding fields using the GraphQLObjectType_fields hook, a type is required.

However, creating a type using the existing api is quite intricate. For example, creating a type like [Orders!]! requires something along these lines: new build.graphql.GraphQLNonNull(new build.graphql.GraphQLList(new build.graphql.GraphQLNonNull(build.getTypeByName('Orders'))))

Maybe a utility method to parse a type string like '[Orders!]!' and return a type instance?

Motivating example

See https://discord.com/channels/489127045289476126/1296863704364879902/1298239516821426236

Breaking changes

Don't think so

Supporting development

I [tick all that apply]:

• am interested in building this feature myself
• am interested in collaborating on building this feature
• am willing to help testing this feature before it's released
• am willing to write a test-driven test suite for this feature (before it exists)
• am a Graphile sponsor ❤️
• have an active support or consultancy contract with Graphile