Subgraph: Helpers for Introspection Query

[banasa44]

Description

To generate the documentation for Subgraph, we are going to use the introspection query, which will read from the schema.graphql itself because the API Endpoint introduces a lot of redundant information.

To do so, we need to declare the scalars Bytes and BigInt that don't exist in GraphQL (the comments are optional, I added so if someone reaches them in the documentation).

And also we need to initialize a Query type, again the comments are optional.

Task ID: OS-1136

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• I have selected the correct base branch.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• My changes generate no new warnings.
• Any dependent changes have been merged and published in downstream modules.
• I ran all tests with success and extended them if necessary.
• I have updated the CHANGELOG.md file in the root folder.
• I have updated the DEPLOYMENT_CHECKLIST file in the root folder.
• I have updated the UPDATE_CHECKLIST file in the root folder.