Fix LoginView and RegisterView response schema generation

[philipkimmey]

Hello! Due to use of serializers.SerializerMethodField() the generated OpenAPI schema wasn't previously accurate.

The schema will vary based on some project settings values, but with the default values the /login/ endpoint previously looked like:

  /login/:
    post:
      operationId: createLogin
      description: 'Check the credentials and return the REST Token

        if the credentials are valid and authenticated.

        Calls Django Auth login method to register User ID

        in Django session framework


        Accept the following POST parameters: username, password

        Return the REST Framework Token Object''s key.'
      parameters: []
      requestBody:
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/Login'
          application/x-www-form-urlencoded:
            schema:
              $ref: '#/components/schemas/Login'
          multipart/form-data:
            schema:
              $ref: '#/components/schemas/Login'
      responses:
        '201':
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Login'
          description: ''
      tags:
      - login

(Which of course isn't the correct response payload)

And now looks like:

  /login/:
    post:
      operationId: createLogin
      description: 'Check the credentials and return the REST Token

        if the credentials are valid and authenticated.

        Calls Django Auth login method to register User ID

        in Django session framework


        Accept the following POST parameters: username, password

        Return the REST Framework Token Object''s key.'
      parameters: []
      requestBody:
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/Login'
          application/x-www-form-urlencoded:
            schema:
              $ref: '#/components/schemas/Login'
          multipart/form-data:
            schema:
              $ref: '#/components/schemas/Login'
      responses:
        '201':
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Token'
          description: ''
      tags:
      - login

[philipkimmey]

TODO: Add tests

[philipkimmey]

TODO: Add tests

[philipkimmey]

TODO: Add tests