Return user's groups as a Terraform data source for templates

[bpmct]

There may be cases where a template wants to be aware of the user's groups for infrastructure to provision/tags to add, etc.

The easiest way to do it seems like sending them as an array of strings in https://registry.terraform.io/providers/coder/coder/latest/docs/data-sources/workspace

data.coder_workspace.me.owner_groups
# ["devops", "platform-engineering", "backstage"]

Use cases

User must be in devops group for this to be provisioned as a part of their workspace:

resource "special_resource" "for_devops" {
  count = contains(data.coder_workspace.me.owner_groups, "devops") ? 1 : 0
}

Add groups as a tag to an resource:

resource "aws_instance" "example" {
  tags = {
    Name        = data.coder_workspace.me.name
    OwnerGroups = join(",", data.coder_workspace.me.owner_groups)
  }
}

Look up IAM policy based on groups:

data "aws_iam_policy" "dynamic" {
  count = length(data.coder_workspace.me.owner_groups)
  arn   = "arn:aws:iam::aws:policy/${element(data.coder_workspace.me.owner_groups, count.index)}"
}

[bpmct]

From #7191

this is blocking org-wide adoption at a major prospect. current state is limiting them to a single team. use-case:

they want to isolate groups to specific namespaces. multiple groups are assigned to a single template, but they want the template to deploy the pod into the user's group namespace (doing this via parameters, but can't validate group)

[f0ssel]

I can take a look at this if that's cool, it's unfamiliar territory but I'd like to learn more in this area.

[matifali]

Who ever is going to take this. We should probably do coder/terraform-provider-coder#180 first before adding any major features to the provider. This will save us from any accumulated tech debt and probably will allow a more streamline process to add new features to the provider.

[f0ssel]

@matifali My change was just a few lines of code, so I wouldn't want that refactor to block this.

[matifali]

It would be nice to publish docs for a use case or a guide on how groups can be used within templates.
The original issue body of this issue, #7191 and #11807 are some possible examples.