Cubes using sql_table cant be exented with sql

[thePermission]

Describe the bug Hey Guys, i tried to follow: https://cube.dev/docs/product/data-modeling/concepts/polymorphic-cubes and https://cube.dev/docs/product/data-modeling/concepts/code-reusability-extending-cubes but if you use sql_table in your base cube and sql in your extended cube, then u get the error: You must use either sql or sqlTable within a model, but not both

To Reproduce

1. Create a Base Cube like this:

   cubes:
   - name: users
   sql_table: users

2. Extend the Base Cube like this:

   cubes:
   - name: teachers
   extends: users
   sql: >
     SELECT * FROM {users.sql()} WHERE type = 'teacher'
   
   - name: students
   extends: users
   sql: >
     SELECT * FROM {users.sql()} WHERE type = 'student'

Expected behavior I would expect the sql attribute to overwrite the sql_table

[igorlukanin]

It makes sense to make he sql parameter to supersede the sql_table one. However, I think this is rather a feature request than a bug since a correct error message is provided by Cube now.