feat: add unit & e2e tests

[nohehf]

Tests

unit

• TypeFormater
• introspection to collection -> then check the validity of the queries with graphql.parse

e2e

• Endpoint to collection
  • should use our own API?
  • can maybe parse it with postman and insomnia CLIs

[nohehf]

I believe that we should include a graphql api in the graphman repo for testing purposes.