Allow users to provide a custom Devfile via the Workspace API during creation, without requiring it to be committed to the repository. This enables more flexible and dynamic workspace setups, especially for ad-hoc configurations. ### Proposal - Extend the Workspace creation API to accept a custom devfile field - Open Question: What's the format of this field? - If provided, this Devfile should override any Devfile in the repository (if any). - Ensure validation and fallback behaviour is clear (e.g., use repo Devfile if none provided).