Integrating with GraphQL API Explorer

[cf-ypark]

Summary

Team: Data Team

Two major updates here

• Added a graphql-api-explorer code block plugin
• Updated most of executable GraphQL code block to add graphql-api-explorer metadata.
• See the CONTRIBUTIONS.md for usage.

Screenshots (optional)

Documentation checklist

• The documentation style guide has been adhered to.
• If a larger change - such as adding a new page- an issue has been opened in relation to any incorrect or out of date information that this PR fixes.
• Files which have changed name or location have been allocated redirects.

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