(graphcache) - Replace buildClientSchema with lean implementation

[kitten]

Summary

Our largest impact on @urql/exchange-graphcache is our usage of graphql/utilities/buildClientSchema which uses GraphQLSchema and other heavy implementations, which are basically server-side implementations with a lot of invariants. Given that we know that with @urql/introspection and other introspection methods the result can be trusted we don't even need any of the strict validation of buildClientSchema and what it pulls in.

Furthmore, we don't need any of the graphql/type/definition types, e.g. GraphQLObjectType and helpers like isObjectType if we transform the client schema to a format that is just good enough for our purposes.

This change increases @urql/exchange-graphcache's size slightly from 6.74kB gzip to 6.93kB gzip. However, the impact on what's pulled in from graphql is significant and we save in -9.61kB gzip (up to; lowest, 8.53kB). This makes a net impact of -9.42kB gzip

Set of changes

• Reimplement buildClientSchema and replace GraphQLSchema types
• Started to drill down buildClientSchema to what's necessary, but then transitioned to just using string-based schema structure
• Update store.ts and schemaPredicates.ts to use new implementation

No unit tests had to be updated, which is encouraging.
The only remaining usage of graphql compared to @urql/core is valueFromASTUntyped

[changeset-bot]

🦋 Changeset detected

Latest commit: 936721e

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

This PR includes changesets to release 1 package

Name	Type
@urql/exchange-graphcache	Patch

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[JoviDeCroock]

Awesome work, wooooooooow