Adds a GraphQL tool window: schema discovery from graphql-config files (or every GraphQL file without one), schema errors and endpoints, running the operation at the caret against a configured endpoint with ${NAME} environment variables, Query Result, and introspection into the schema file. The editor gets a GraphQL toolbar with endpoint selection, variables and run.
The tool window is listed on the stripe once used, so projects without GraphQL get no extra button.
Closes#1168
Co-authored-by: kidp2h <[email protected]>
