fix: sub-type handling in hashing logic

[julrich]

When resolving components, we currently jump through some hoops to hash / de-hash objects and keys, to satisfy the GraphQL query rules.

There seems to be a break-down between the two parts generating the initial GraphQL and fragments inside kickstartDS-schema-toolkit and the part where we de- / encode those in this theme:

• https://github.com/kickstartDS/gatsby-theme-kickstartDS/blob/master/gatsby-transformer-kickstartds-netlify-cms/gatsby-node.js#L19-L50
• https://github.com/kickstartDS/kickstartDS-schema-toolkit/blob/master/jsonschema2graphql/src/schemaReducer.ts

This results in problems that need to be explicitly handled in the theme, now. Those should be cleaned up in the process:

• https://github.com/kickstartDS/gatsby-theme-kickstartDS/blob/master/gatsby-transformer-kickstartds-netlify-cms/gatsby-node.js#L29
• https://github.com/kickstartDS/gatsby-theme-kickstartDS/blob/master/gatsby-transformer-kickstartds-netlify-cms/gatsby-node.js#L38