Upload Schema Asset for releases

[jasonbahl]

Much like WPGraphQL uploads a Schema asset for releases, it would be nice for WPGraphQL for ACF to do similar so we could automate Schema diffs.

In order to do this, we would also need to use a consistent ACF Field Group configuration so we could show how it's been impacted by changes over time.

We have this field group: https://github.com/wp-graphql/wp-graphql-acf/blob/develop/docs/field-group-examples-export.json

We could use that in a Github workflow, import it, generate the schema, upload the schema asset, diff the schemas on next release.

We could potentially do this with more than one field group / sets of field groups too 🤔

[jasonbahl]

Closed by #279

We can now see the Schema.graphql being generated and uploaded to the releases: https://github.com/wp-graphql/wp-graphql-acf/releases/tag/v0.5.3