GraphQL equivalent API as REST "/v1/sql"?

**Is your feature request related to a problem? Please describe.**
REST have `/v1/sql` API to get the SQL Code generated by Cube to be executed in the database.
https://cube.dev/docs/rest-api#api-reference-v-1-sql

However, for a GraphQL query, there seems no equivalent API. It is a nice to have feature, maybe helpful to debug whether the query is expected. e.g. https://github.com/cube-js/cube.js/issues/4387
(btw, playground may help, but for production, playground is normally turn off)

**Describe the solution you'd like**
GraphQL equivalent API as REST "/v1/sql". Still `/graphql` endpoint, but provide a different query type?

**Describe alternatives you've considered**
A clear and concise description of any alternative solutions or features you've considered.

**Additional context**
Add any other context or screenshots about the feature request here.