Add API that receives GraphQL query input and returns generated SQL statements

[karatakis]

Motivation

Currently the project has some unit tests and some integration tests.

The drawbacks are that unit tests are simple and integration tests require infrastructure.

Proposed Solutions

• Create and API that receives GraphQL query input and return SQL statements
• Use proposed API to test various scenarios

Additional Information

The advantage is that we can inspect SQL queries without needing a database to execute them.