feat: add environment files support and scotty file download helper

[copybara-service]

feat: add environment files support and scotty file download helper

[2ynn]

IIUC client.environments.with_raw_response.files does the following:

1. GeminiNextGenEnvironments.with_raw_response proxies to Environments.with_raw_response -> EnvironmentWithRawResponse
2. calls __getattr__('files') on EnvironmentWithRawResponse -> self._sdk.files.with_raw_response
3. self._sdk.files is the wrapper's files property so returns _files_wrapper = plain GeminiNextGenEnvironmentFiles with no with_raw_response -> AttributeError: 'GeminiNextGenEnvironmentFiles' object has no attribute 'with_raw_response'

Same thing expected for client.environments.with_streaming_response.files

I think it would be wise to add tests for with_raw/streaming_response helpers

[2ynn]

I don't think these should be nested under if not TYPE_CHECKING. By doing so mypy could raise a "Files" has no attribute "download" for client.environments.files.download(...)` for example

Suggested change

	@property
	def files(self) -> GeminiNextGenEnvironmentFiles:
	return getattr(self, '_files_wrapper', None)
	@files.setter
	def files(self, value: Any) -> None:
	self._sdk_files = value
	@property
	def files(self) -> GeminiNextGenEnvironmentFiles:
	return getattr(self, '_files_wrapper', None)
	@files.setter
	def files(self, value: Any) -> None:
	self._sdk_files = value

[2ynn]

Could streamline by initializing files: GeminiNextGenEnvironmentFiles instead of self._files_wrapper:

class GeminiNextGenEnvironments(GeneratedEnvironments):
    """Public environments resource backed by the NextGen client."""

    files: GeminiNextGenEnvironmentFiles

    def __init__(self, api_client: Any):
        self._api_client = api_client
        sdk = build_google_genai_client(api_client)
        super().__init__(sdk.sdk_configuration, parent_ref=sdk)

    def _init_sdks(self) -> None:
        self.files = GeminiNextGenEnvironmentFiles(
            self.sdk_configuration,
            parent_ref=self.parent_ref,
            api_client=self._api_client,
        )

Suggested change

	@property
	def files(self) -> AsyncGeminiNextGenEnvironmentFiles:
	return getattr(self, '_files_wrapper', None)
	@files.setter
	def files(self, value: Any) -> None:
	self._sdk_files = value

[2ynn]

Same comment as https://github.com/googleapis/python-genai/pull/2861/changes#r3833970383

[2ynn]

It seems inconsistent to normalize the environment path in download() but not list() (where we pass args directly to async_wrap_sdk_call(files_sdk.list, *args, **kwargs))