[Snapshots] Adapter maintainer functional tests for snapshot configs in dbt-core v1.9

[dbeatty10]

Housekeeping

• I am a maintainer of dbt-adapters

Short description

Add the functional tests here into the dbt-tests-adapter section here.

Context

We want adapter maintainers to be able to test their snapshot materialization macros against the snapshot configs introduced in dbt-core v1.9.

Acceptance criteria

Tasks

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1. Adapter maintainers can inherit these functional tests and override as-needed

Testing

Tasks

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1. Expect pass for all of these tests.

Security

None

Docs

Add the final names of the test classes to the adapter maintainer guide so that adapter maintainers know how to inherit them.

Consequences

Adapter maintainers won't be able to inherit these tests until this is implemented. In the meantime, they could copy-paste the code from here (along with any relevant fixtures).