JSON schema aggregation should use unevaluatedProperties in global properties

[fstaudt]

JSON schema aggregated-values.schema.json is currently generated with .properties.global.additionalProperties set to false:

{
  "properties": {
    "global": {
      "additionalProperties": false,
      "allOf": [
        {
          "$ref": "..."
        },
        {
          "$ref": "..."
        },
        {
          "title": "Aggregated global values for chart",
        }
      ]
    }
  }
}

According to JSON schemas specification, unevaluatedProperties should be used instead to ensure correct validation after schema composition:

{
  "properties": {
    "global": {
      "unevaluatedProperties": false,
      "allOf": [
        {
          "$ref": "..."
        },
        {
          "$ref": "..."
        },
        {
          "title": "Aggregated global values for chart",
        }
      ]
    }
  }
}

Flag additionalProperties should also be removed from sub-schemas in aggregated JSON schema when schemas are composed with allOf.

Current usage of additionalProperties cause incorrect validation errors in VS code and in gradle task validateHelmValues implemented with https://github.com/networknt/json-schema-validator.