Update Girder4 TF module

[mvandenburgh]

This PR upgrades the girder/girder4/heroku module to 0.12.0. I'll follow up with another PR that bumps it to 0.13.0 (the latest), but the jump from 0.11.0->0.12.0 includes by far the more complex/annoying breaking changes.

Things to note:

• v0.12.0 does a major version upgrade for the AWS and Heroku providers; the breaking changes for Heroku aren't too bad, but the AWS provider significantly changed how S3 buckets are represented in Terraform and introduced several new resource types (docs). I've added a temporary file, terraform/imports.tf, to handle the imports of these new resources into the existing TF state.

  • Note: it seems that there's two options to handling this transition, either (1) import these resources (as I do in this PR), or (2) just adding them and doing an apply. At least, that's what I get from this paragraph in the upgrade guide; assuming I'm interpreting it correctly, I think importing is safer than applying.

  • Depending on the tools available to you, the above configuration can either be directly applied with Terraform or the standalone resource can be imported into Terraform state. Please refer to each standalone resource's Import documentation for the proper syntax.

• There are currently two empty S3 buckets sitting in AWS that are managed by the girder/girder4/heroku module. These are the module.api.module.storage.aws_s3_bucket_acl.storage and module.api_staging.module.storage.aws_s3_bucket_acl.storage resources in the TF plan below. We should remove these at some point, but for the purposes of this PR I didn't touch them.

[mvandenburgh]

even though the plan looks pretty confusing.

yup :frowning_face: I included a more detailed explanation of what's going on in the PR description, which I just posted shortly before you approved this.