Add ability to map custom scalar types

[vladar]

At the moment, any custom scalar type is replaced with the most generic JSON type. We should allow you to define a map of remoteScalarType => gatsbyScalarType in the config.

Technically it is also possible now by overriding toolkit's types with schema customization. But it is tedious as it has to be done per-field (so if you have fields of type Timestamp on 100 different types, you will have to add 100 type definitions manually).

[vladar]

One way to go with it (that is also generic enough) is to allow custom field transformers in sourcing config here:

gatsby-graphql-toolkit/src/create-schema-customization/transform-fields/field-transformers.ts

Line 27 in d3fd087

export const fieldTransformers: IGatsbyFieldTransform[] = [

[aaronadamsCA]

Just ran into this. Couldn't figure out why Gatsby revised gatsbyImageData to be of scalar type GatsbyImageData, but our generated schema from our remote source still shows JSON.

Any chance this toolkit gets some love anytime soon, @vladar, or is it dead?