Clarify batch testing strategies

[tombaeyens]

Create prescriptive approach and docs on how to choose and implement each of the supported strategies.

Background:

• https://discourse.getdbt.com/t/on-the-limits-of-incrementality/303
• https://medium.com/geekculture/idempotent-data-pipeline-with-dbt-and-airflow-597d6f65a811
• https://techblog.finatext.com/dbt-incremental-strategy-and-idempotency-877993f48448

[tools-soda]

CLOUD-8490