message: Add overlays to configuration schema
diff: "type": "string",
  "description": "A message to print if this entry is evaluated."
  },
  + "overlay-ports": {
  + "type": "array",
  + "description": "An array of port overlay paths.",
  + "items": {
  + "type": "string"
  + }
  + },
  + "overlay-triplets": {
  + "type": "array",
  + "description": "An array of triplet overlay paths.",
  + "items": {
  + "type": "string"
  + }
  + },
  "requires": {
  "description": "Artifacts that are required for this package to function.",
  "$ref": "vcpkg-schema-definitions.schema.json#/definitions/artifact-references"
  