Add an endpoint to get final SQL query (not parameterized)

**Is your feature request related to a problem? Please describe.**
The endpoint `/cubejs-api/v1/sql` returns a parameterized query which is of no use.

**Describe the solution you'd like**
An endpoint that returns the final SQL request ready to be pasted in DB ide (to debug and test).

**Describe alternatives you've considered**
Manually replace the `?` with filters value but it is error prone and tiresome.

**Additional context**
related to https://github.com/cube-js/cube.js/issues/4614