[2/3] DXCDT-234: Fix update behavior of client_metadata

[sergiught]

🔧 Changes

To correctly remove a key from the client_metadata object we need to send it as null to the API. So we're fixing the behavior of the client_metadata expand to account for this.

POST /client
{
  "client_metadata": {
    "foo": "bar",
    "faa": "removeMe"
  }
}

PATCH /client
{
  "client_metadata": {
    "foo": "bar",
    "faa": null
  }
}

GET /client
{
  "client_metadata": {
    "foo": "bar"
  }
}

📚 References

• DXCDT-234: Change ClientMetadata to *map[string]interface{} go-auth0#120

🔬 Testing

📝 Checklist

• All new/changed/fixed functionality is covered by tests (or N/A)
• I have added documentation for all new/changed functionality (or N/A)

[Widcket]

CI is failing

[sergiught]

@Widcket , CI was failing as we needed to merge #369 first. They're cascading as they're all depending on changes from v0.12.0 of the go SDK. All green now -> https://github.com/auth0/terraform-provider-auth0/actions/runs/3278934803/jobs/5397902694