Minor schema validation error: doesn't complain about invalid default for null and file types

Describe the bug
NoneProperty.build and FileProperty.build do have logic to detect if a default other than None was provided for a null property, or if any default was provided for a binary string—and we do have unit tests for those. However, in reality NoneProperty.build and FileProperty.build do not actually get called, because property_from_data just calls the initializers directly instead. Therefore if you do something like this, the default is simply ignored.

OpenAPI Spec File

components:
  schemas:
    MyModel:
      properties:
        myNullProperty:
          type: "null"
          default: "definitely not null"
        myBinaryString:
          type: string
          format: binary
          default: "???"

Desktop (please complete the following information):

• OS: any
• Python Version: any
• openapi-python-client version: 0.21.6

首先跟踪 property_from_data，并将其对 initializer 的直接调用与 NoneProperty.build 和 FileProperty.build 进行比较，后者已经包含验证逻辑。运行这些 builder 的现有单元测试，然后添加测试覆盖，以表明所提供的 OpenAPI schema 中的无效默认值会被拒绝，而不是被忽略。