Enable audits in model defaults

[AronsonDan]

The scenario goes as follows:

1. table which is defined as an external source was ingested and serves as a base table
2. that table has some meta fields that i would like to drag along downstream the models
3. Would love to test all across the transformations in that model that the columns exists and to fail a plan in case it dosent

suggestion: enable model level audits

model_defaults:
  dialect: snowflake
  audits:
    - assert_base_columns