cube_dbt does not handle all dbt model contract data types from Snowflake

[jmkacz]

Looking at https://github.com/cube-js/cube_dbt/blob/main/src/cube_dbt/column.py#L29-L45, cube_dbt only maps a handful of types to cube.dev's five (5) supported dimension types (https://cube.dev/docs/reference/data-model/types-and-formats#dimension-types).

The documentation on cube.dev's site states that there are only a few supported types, but not why only those.

Column types should match dimension types or a few supported aliases:
-- https://cube.dev/docs/reference/python/cube_dbt

We are using Snowflake, dbt, cube.dev, and cube_dbt.

The following contract snippet builds successfully in dbt IDE, but our developers want to be more specific (ex. data_type: timestamp_ntz) and :

      - name: last_modified_at_utc
        description: >
          {{ doc("last_modified_at_utc") }}
        data_type: timestamp

We then get the following error:

Unknown column type of <MODEL>.<COLUMN>: timestamp_ntz

from this line of code: https://github.com/cube-js/cube_dbt/blob/main/src/cube_dbt/column.py#L47

[jmkacz]

I have a PR I would like to file that covers all existing Snowflake data types in the type mapping dict.

[jmkacz]

Here are my proposed changes: #10