Create a pre-signed URL to send feedback data to.
This is useful for giving browser-based clients a way to upload feedback data directly to LangSmith without accessing the API key.
The expiration time of the pre-signed URL. Either a datetime or a timedelta offset from now. Default to 3 hours.
If creating a feedback_key for the first time, this defines how the metric should be interpreted, such as a continuous score (w/ optional bounds), or distribution over categorical values.
