[Feature] Migrate dbt-tests-adapter

[mikealfare]

Is this your first time submitting a feature request?

• I have read the expectations for open source contributors
• I have searched the existing issues, and I could not find an existing issue for this feature
• I am requesting a straightforward extension of existing dbt-adapter functionality, rather than a Big Idea better suited to a discussion

Describe the feature

Grab all of the pieces that build into dbt-tests-adapter and host them as a namespace package in dbt-adapters.

Describe alternatives you've considered

No response

Who will this benefit?

No response

Are you interested in contributing this feature?

No response

Anything else?

No response