Feature: Custom Iceberg base_location_root

[LProcopi15]

resolves #1284
Related docs

Problem

Currently, we only allow users to append a base_location_subpath to a base_location when creating a Snowflake Iceberg table. We've hard coded in the base_location root to be _dbt/<schema-name>/<table-name>.

Some customers have requested we allow overrides of the top-level _dbt/ directory. After discussing with product (@amychen1776), we've decided to add support for this.

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Solution

Add a new optional config for Snowflake called base_location_root. If this is provided, it will override the default dbt base_location value (_dbt/<schema_name>/<table_name>/) to base_location_root/<schema_name>/<table_name>/)

Examples from test runs:

Configs for _MODEL_BASIC_ICEBERG_MODEL: base_location_subpath="subpath", (no base_location_root). Snowflake ddl generated:

create or replace iceberg table analytics.test17370768401216806666_test_table_basic.iceberg_table
 ...
        base_location = '_dbt/test17370768401216806666_test_table_basic/iceberg_table/subpath'
...

Configs for _MODEL_BASIC_ICEBERG_MODEL_WITH_PATH: base_location_root="root_path", (no base_location_subpath). Snowflake ddl generated:

create or replace iceberg table analytics.test17370768401216806666_test_table_basic.iceberg_tableb
...
      base_location = 'root_path/test17370768401216806666_test_table_basic/iceberg_tableb'
....

Configs for _MODEL_BASIC_ICEBERG_MODEL_WITH_PATH_SUBPATH: base_location_root="root_path", base_location_subpath="subpath",. Snowflake ddl generated:

create or replace iceberg table analytics.test17370768401216806666_test_table_basic.iceberg_tablec
...
     base_location = 'root_path/test17370768401216806666_test_table_basic/iceberg_tablec/subpath'
...

Validation of Tests

See passing functional & unit tests in CI

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Checklist

• I have read the contributing guide and understand what's expected of me
• I have run this code in development and it appears to resolve the stated issue
• This PR includes tests, or tests are not required/relevant for this PR
• This PR has already received feedback and approval from Product or DX
  @amychen1776 and I have discussed and aligned on these changes.

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[github-actions]

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[mikealfare]

Looks good. There are two issues that look like copy paste errors and then a nice to have if you feel like it and think it would be better than what you have.