The Get temporary credentials endpoint will return temporary credentials that can be used to stage or retrieve content. Use this endpoint with action "put-contentstore" to get temporary credentials to stage the content for upload on the Nebula contentstore. Use temporary credentials in lieu of getStagingUrl to stage large files using multi-part upload or stage large number of files. The returned credentials will allow put object access to the contentstore S3 bucket for the stack/tenant and only to the prefix returned in the response. Credentials are valid for an hour. Cache the credentials and use it for multiple files. Use this end-point with action "get-thumbnail" to get credentials to retrieve thumbnails. Defaults to "put-contentstore". Do not use "put-dropzone" unless specified by the Nebula team.