Assume IAM role during cloud agent build step

Feature request for product/service

Cloud Agent (GitHub, Slack, Linear,…)

Describe the request

Allow assumption of defined IAM role during cloud agent Docker build step to e.g. pull a base image from private ECR when defining a cloud agent image via Cloud Environment Setup | Cursor Docs. Currently, IAM roles are only supported during install, after the image has already been built. Split off from Create Cursor cloud agent with AWS IAM roles without Bedrock - #11 by kkchau.