[record_use] Implementation: JSON: Separate recordings of instances and calls

[dcharkes]

The recordings contain both recordings of instances and of static calls - but the fields that are required are not the same, leading to an underspecified schema.

For const instances only the instances property should and must be supplied. And for static calls only the calls property should and must be supplied.

It would be cleaner to separate them.

{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "$ref": "#/definitions/RecordedUses",
  "definitions": {
    // ...
"RecordedUses": {
      "type": "object",
      "properties": {
        // ...
        "recordings": {
          "type": "array",
          "items": {
            "$ref": "#/definitions/Recording"
          }
        }
      },
      // ...
    },
    "Recording": {
      "type": "object",
      "properties": {
        "calls": {
          "type": "array",
          "items": {
            "$ref": "#/definitions/Call"
          }
        },
        "definition": {
          "type": "object",
          "properties": {
            "identifier": {
              "$ref": "#/definitions/Identifier"
            },
            "loading_unit": {
              "type": "string"
            }
          },
          "required": [
            "identifier"
          ]
        },
        "instances": {
          "type": "array",
          "items": {
            "$ref": "#/definitions/Instance"
          }
        }
      },
      "required": [
        "definition",
        // cannot list calls or instances
      ]
    }
  }
}

(Split from #1093)