Log `used_fields` information on GraphQL API

What does this MR do?

This MR introduces new log parameters for the GraphQL API which are used_fields and used_deprecated_fields. I am planning to utilize these new log parameters to build new graphs on Kibana.

Extra: Also the way we store the logs for GraphQL API makes it impossible(please correct me if I'm wrong) to track the requests. Since we are putting the GrahpQL logs into separate file, even though we have the correlationID, there is no way to match the GraphQL logs with the Rails logs as there is no parent-child relationship defined in the mapping of the logs document. What was the reason for putting them into separate files?

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Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

• [-] Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• [-] Label as security and @ mention @gitlab-com/gl-security/appsec
• [-] The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• [-] Security reports checked/validated by a reviewer from the AppSec team