Represents a custom const type definition in a JSON schema.

JSON Schema:

"favoriteNumber": {
  "type": "integer",
  "const": 42
}

or

"testStruct": {
  "const": {
    "name": "Test",
    "foo": 43
  }
}

Resulting in the Elixir representation:

%ConstType{name: "favoriteNumber",
           description: nil,
           type: :number,
           path: URI.parse("#/favoriteNumber"),
           const: 42}

or

%ConstType{name: "testStruct",
           description: nil,
           type: :object,
           path: URI.parse("#/testStruct"),
           const: %{"name" => "Test", "foo" => 43}}