feat(python): Add client for test results.

[ian-sift]

Added new integration test that exercises new client

[alexluck-sift]

Generally looks good, but please take a pass for consistency with the existing Resources. I called out some of these.

Also: https://github.com/sift-stack/sift/blob/main/python/lib/sift_client/_internal/CONTRIBUTING.md

[alexluck-sift]

An Idea to have consistency in namespacing and also clear differentiation between functions acting on different types would be to break these out into multiple "resources" within the same TestResults namespace. This may be a good pattern to keep things organized and leverage the same function names.

What do you think?

class TestResultsStepsAPIAsync(ResourceBase):
    def __init__(self, sift_client: SiftClient):
        super().__init__(sift_client)
        self._low_level_client = TestResultsLowLevelClient(
        grpc_client=self.client.grpc_client
        )

    def create(self) -> TestStep: ...
    def list_(self) -> list[TestStep]: ...
    ...

class TestResultsMeasurementsAPIAsync(ResourceBase):
    def __init__(self, sift_client: SiftClient):
        super().__init__(sift_client)
        self._low_level_client = TestResultsLowLevelClient(
            grpc_client=self.client.grpc_client
        )

    def create(self) -> Measurement: ...
    def list_(self) -> list[Measurement]: ...
    ...

class TestResultsAPIAsync(ResourceBase):
    def __init__(self, sift_client: SiftClient):
        super().__init__(sift_client)
        self._low_level_client = TestResultsLowLevelClient(
            grpc_client=self.client.grpc_client
        )
        self._upload_client = UploadLowLevelClient(rest_client=self.client.rest_client)
        
        self.steps = TestResultsStepsAPIAsync(self.client)
        self.measurements = TestResultsMeasurementsAPIAsync(self.client)

    def create(self) -> TestReport: ...
    def list_(self) -> list[TestReport]: ...
    ...

# Usage
client = SiftClient(api_key="your_api_key")
test_result = client.test_results.create(...)
test_step =  client.test_results.steps.create(...)
test_measurement = client.test_results.measurements.create(...)

[alexluck-sift]

looks good!