[copilot] agent output collection

[pelikhan]

Your task is to update the generated code in the lock file to support exposing outputs from the agentic engine as workflow output variables.

The changes should be applied to the agentic-job code generation:

• as a prestep, set an environment variable GITHUB_AW_OUTPUT pointing to a temp file (under /tmp, random filename). Use JavaScript + actions/github-script.
• generate a prompt that automatically gets injected into the agent prompt file that tells the agent to write the user requested output to the GITHUB_AW_OUTPUT file. Make sure GITHUB_AW_OUTPUT is passed to the agentic engine and it has rights to write to it.
• add a post step after the agentic engine run that reads the GITHUB_AW_OUTPUT and if there is content adds it to the actions outputs under the key "output". Use JavaScript + actions/github-script.
• declare the agentic job output "output" as the agentic engine engine in the workflow yaml