Add integration test with terraform provider

We have an integration tests in coder/terraform-provider-envbuilder that tests that the provider works with a given version of envbuilder.

It would be useful to have a similar test in envbuilder that tests that envbuilder works with a given version of the provider.

首先检查 coder/terraform-provider-envbuilder 中现有的集成测试以及 envbuilder 周围的测试设置。针对反向关系复现其 provider 版本兼容性覆盖范围，并让测试在 envbuilder 能够与所选 provider 版本正常工作时通过。

由索引模型根据 Issue 内容生成。