feat: Sync codegen behavior implementation adding generateModelsSync

[stocaaro]

Description of changes

This change translates the vendored code for codegen, adapting it so that it isn't async. Steps to adapt the code have been made as simple as possible where complexity is captured in related code to make upgrades as easy as possible as we maintain this. Directions are documented.

• Document and apply the MAINTENANCE.md adaptations to the @graphql-codegen/core fork
• Add a bunch of derived types to support sync codegen
• Add sync preset/plugin implementation
• Fix test errors caused by how jest hoisting works with mocks

Suggested review pattern:

1. Copy the @graphql-codegen/core file across
   1. This change adds the version checking and copies across an unmodified version of @graphql-codegen/core.
   2. The code in the vendor folder will be an exact copy in this diff.
2. Modify libraries to expose codegenSync behavior
   1. This diff covers all of the work to:
      1. Modify the vendored core code to be sync
      2. Add sync preset/plugin code to the plugins package
      3. Adds the sync types to the plugins package
      4. Add the generateModelsSync implementation
      5. Add CODEOWNERS requirement to get admin review for vendor changes

The copied code has been modified as little as possible and it is not intended to conform to local repo patterns as this would make future maintenance more difficult

Codegen Paramaters Changed or Added

const c = codegenSync(...);
// which is the same as without any async behavior
// const c = await codegen(...);
//
// Used to implement:
generateModelsSync(...)
// which is a sync version of
// generateModels(...)

generateModelsSync implementation

Description of how you validated changes

Checklist

• PR description included
• yarn test passes
• Tests are changed or added
• Changes are tested using sample applications for all relevant platforms (iOS/android/flutter/Javascript) that use the feature added/modified
• Changes are tested on windows. Some Node functions (such as path) behave differently on windows.
• Changes adhere to the GraphQL Spec and supports the GraphQL types type, input, enum, interface, union and scalar types.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[stocaaro]

Without this change, our code depends on 2 versions of core. Applying this so that we only have a single version in our dependency list for the monorepo

[stocaaro]

Including the version check in the build process. As discussed, this will push the developer to look at the maintenance instructions if the version from npm is different than the one adapted in the vendor folder.