Fix/recursive types

[lpoulier-vhs]

I encountered two issues when attempting to use this plugin:

1. The kind variable is always undefined, so no otherUsedTypes are ever processed. This is due to the resolvedType.astNode always being undefined. issue link
2. The code would enter an infinite loop if the graphql schema contains circular references. issue link

These issues are resolved by:

1. Implementing a workaround from this issue to get all astNode fields in the schema to be properly generated when loading the schema.
2. Instantiate a Set to store names of input types that are already processed, add input types when they are first processed, and prevent infinite loop by skipping these if encountered more than once.