[json] create links for values of format `uri-reference`

<!-- ⚠️⚠️ Do Not Delete This! feature_request_template ⚠️⚠️ --> <!-- Please read our Rules of Conduct: https://opensource.microsoft.com/codeofconduct/ --> <!-- Please search existing issues to avoid creating duplicates. --> <!-- Describe the feature you'd like. --> When authoring json it'd be great to have a richer experience when referencing other files, without having the overhead of defining a `file://` URI whenever this is required (see example below).  I would expect this behaviour by standard when the schema is defining the values as file-references, this is also related to my more pertinent issue in the vscode-yaml repository concerning the handling of k8s kustomize resources ([vscode-yaml#559](https://github.com/redhat-developer/vscode-yaml/issues/559))