Extend GraphQL store config implementation

[nuzil]

For PWA frontend implementation we need to extend list of parameters which we need to ability to receive from Magento Configuration.

Base implementation: #126
PWA Requirements: magento/pwa-studio#115

At this moment values we need are:

Content -> Design -> Configuration:

• HTML head Section
• Header Section
• Footer section
• Others are not really required at this moment.

Stores -> Configuration

• Web -> Default Pages (current blocker, cause we need to know correct pages ID. Otherwise we have to hardcode them).

Catalog | Catalog -> Search Engine Optimization: Category URL Suffix

Implementation

Will be nice to have possibility to define list of config parameters that user can request via GraphQL by using graphql/di.xml file. So developer could extend this list easily

Result

By Using GraphQL query we can receive parameters described on this issue, list of variables will be based on di.xml configuration file

[naydav]

#182