feat: Add support for persisted documents via the documentId property

[kitten]

Summary

This PR adds support for persisted documents, as long as:

• An input GraphQL AST contains a documentId property
• A GraphQL API accepts the documentId parameter as a replacement for the query parameter

When we detect the documentId property on a document which has no definitions (either an empty array or not defined), we send a documentId instead of a query.

This is similar to Automatic Persisted Queries (APQs), but those require the @urql/exchange-persisted exchange, to facilitate generating persisted queries on the fly (as per the spec) and retrying them.

This is to comply with: graphql/graphql-over-http#264

Set of changes

• Add documentId property to detected GraphQL document types
• Send documentId on FetchBody when a persisted document is passed

[changeset-bot]

🦋 Changeset detected

Latest commit: 33bf2f3

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@urql/core	Minor

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[kitten]

Merging since it technically doesn't matter when we land this exactly