fix: implements graphql schema generation

[JarrodMFlesch]

Description

Fixes payloadcms/payload-3.0-demo#176

The @payloadcms/graphql package now exports a bin script under the scope payload-graphql.

So you can run:

pnpm payload-graphql generate:schema

Also adds the graphQL.schemaOutputFile filepath property back to the payload config. Similar to how the TS types filepath is set with typescript.outputFile.

• I have read and understand the CONTRIBUTING.md document in this repository.

Type of change

• Chore (non-breaking change which does not add functionality)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Change to the templates directory (does not affect core functionality)
• Change to the examples directory (does not affect core functionality)
• This change requires a documentation update

Checklist:

• I have added tests that prove my fix is effective or that my feature works
• Existing test suite passes locally with my changes
• I have made corresponding changes to the documentation