Headless amplify pull without modifying the backend

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[official AWS Amplify Console forum](https://forums.aws.amazon.com/forum.jspa?forumID=314&start=0)

**Is your feature request related to a problem? Please describe.**

There seems to be no way to answer **No** to the question:
**Do you plan on modifying this backend?**
When running headless amplify pull.

I find this annoying in the case of React Native app CI/CD building scripts. I want to build my app on git push, so I need to include the _aws-exports.js_ file which I don't have in the git repo. This feature would allow me to retrieve the amplify project meta data only, in the building script, without updating the project in the cloud.

**Describe the solution you'd like**
I would like a new argument to the headless amplify pull (https://docs.amplify.aws/cli/usage/headless#amplify-pull-parameters) that answers **Yes** or **No** to the question: **Do you plan on modifying this backend?**

**Describe alternatives you've considered**
I can still commit the _aws-exports.js_ file, but it's really annoying when working with teammates on several environments.
The solution I am considering is to host the _aws-exports.js_ files somewhere and download them with a curl in the CI/CD scripts. But that would mean updating those files when amplify project is updated.

Start with the headless amplify pull parameters documented at the linked Amplify CLI page, then trace the headless amplify pull entry point. Done means a new argument answers whether the backend will be modified and allows CI/CD to retrieve the project metadata, including aws-exports.js, without updating the cloud backend.

Written by the indexing model from the issue text.