Schema references using $ref cannot be loaded by DSC engine

Prerequisites

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Summary

When $ref is used to refer to _exists schema from DSC repository, DSC engine fails to access it with the following error:

ERROR Error: Schema: Resource 'https://raw.githubusercontent.com/PowerShell/DSC/main/schemas/v3/resource/properties/exist.json' is not present in a registry and retrieving it failed: resolve-http feature or a custom resolver is required to resolve external schemas via HTTP

Steps to reproduce

1. Resource manifest has:

              "_exist": {
                    "$ref": "https://raw.githubusercontent.com/PowerShell/DSC/main/schemas/v3/resource/properties/exist.json"
                }

Expected behavior

should get the $ref schema

Actual behavior

Error

Error details

ERROR Error: Schema: Resource 'https://raw.githubusercontent.com/PowerShell/DSC/main/schemas/v3/resource/properties/exist.json' is not present in a registry and retrieving it failed: `resolve-http` feature or a custom resolver is required to resolve external schemas via HTTP

Environment data

N/A

Version

3.2.0-preview.3

Visuals

No response

Begin at the DSC engine schema-loading path that emits the resolve-http error, using the resource manifest example with the external $ref to reproduce it. Done means the referenced schema from the DSC repository is loaded successfully instead of producing the registry and resolver error.