Add integration tests for coder -> terraform-provider-coder

# Problem

We don't have any integration tests currently in coder/coder targeting version compatibility with coder/terraform-provider-coder. We do have integration tests the other way round (terraform provider -> coder).

# Proposed Solution

Adding integration tests in the other direction would allow us to validate that any given version of coder will work correctly with any given version of the terraform provider.

Building blocks for this didn't exist previously but were recently added with https://github.com/coder/coder/pull/15897

Beginne damit, die in coder/coder pull request 15897 hinzugefügten Bausteine zu lesen, und finde die bestehenden terraform-provider-coder-to-coder-Integrationstests. Ermittle anhand dieser Tests, wie Kombinationen von Versionen getestet werden. Die Aufgabe ist abgeschlossen, wenn die im Issue beschriebene umgekehrte coder-to-provider-Kompatibilitätsabdeckung hinzugefügt wurde.

Vom Indexierungsmodell aus dem Issue-Text verfasst.