WIP: Add cloudflare_access_group data source

[paulbehrisch]

I am using the Terraform provider and have to retrieve the cloudflare_access_group by name.

I did a quick test and this worked, but it's only exposing the ID and the Name.

I got a deprecation warning for MAXIMUM_ALLOWED_SDKV2_DATASOURCES = 20 and I haven't added any tests yet.
I haven't written Go or a Terraform provider before and only tried to get this working.

With valid access groups:

data.cloudflare_access_group.group1: Reading...
data.cloudflare_access_group.group2: Reading...
data.cloudflare_access_group.group1: Read complete after 0s [id=18238aca-9195-4f1d-b083-83f2b6e866b9]
data.cloudflare_access_group.group2: Read complete after 0s [id=eb21cc8e-da27-4453-bb23-f678f32db63f]

Changes to Outputs:
  + group1_id = {
      + account_id = "123425d31ae24a27770d5fe81341fdd9"
      + id         = "18238aca-9195-4f1d-b083-83f2b6e866b9"
      + name       = "abc"
      + zone_id    = null
    }
  + group2_id = {
      + account_id = "123425d31ae24a27770d5fe81341fdd9"
      + id         = "eb21cc8e-da27-4453-bb23-f678f32db63f"
      + name       = "def"
      + zone_id    = null
    }

With invalid access group:

data.cloudflare_access_group.group2: Reading...
data.cloudflare_access_group.group1: Reading...
data.cloudflare_access_group.group1: Read complete after 0s [id=18238aca-9195-4f1d-b083-83f2b6e866b9]

Changes to Outputs:
  + group1_id = {
      + account_id = "123425d31ae24a27770d5fe81341fdd9"
      + id         = "18238aca-9195-4f1d-b083-83f2b6e866b9"
      + name       = "abc"
      + zone_id    = null
    }

You can apply this plan to save these new output values to the Terraform state, without changing any real infrastructure.
╷
│ Error: no Access Groups matching name "def1"
│
│   with data.cloudflare_access_group.group2,
│   on data.tf line 7, in data "cloudflare_access_group" "group2":
│    7: data "cloudflare_access_group" "group2" {
│

There are also other data sources missing as for device_settings_policy_id. Is this currently on the roadmap of being added?

[github-actions]

Oops! It looks like no changelog entry is attached to this PR. Please include a release note as described in https://github.com/cloudflare/terraform-provider-cloudflare/blob/master/contributing/changelog-process.md.

Example:

```release-note:TYPE
Release note
```

If you do not require a release note to be included and you have permission, please add the workflow/skip-changelog-entry label. Otherwise, a maintainer will add the label or ask you for one when they review the PR.

[jacobbednarz]

thanks for the effort you've take thus far however, as the error points out, we are no longer accepting resources or data source that rely on the SDKv2 internals. if you want to land this, you'll need to submit it using the framework plugin. you can see an example of this in the api_token_permission_groups data source.