Experimental stackmapping changes for Gen2

[AnilMaktala]

Problem

Enabled the stack mapping property in Gen2

Issue number, if available: https://github.com/aws-amplify/amplify-category-api/issues/2550

Corresponding docs PR, if applicable:

Validation

Checklist

• [ ] If this PR includes a functional change to the runtime behavior of the code, I have added or updated automated test coverage for this change.
• [ ] If this PR requires a change to the Project Architecture README, I have included that update in this PR.
• [ ] If this PR requires a docs update, I have linked to that docs PR above.
• [ ] If this PR modifies E2E tests, makes changes to resource provisioning, or makes SDK calls, I have run the PR checks with the run-e2e label set.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: b1681696172387741773635d93256ea3a9ca6c86

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@aws-amplify/backend-data	Minor

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[MarlonJD]

It's just fixing important migration blocker issue #2550. stackMappings is already defined in aws-amplify/amplify-category-api repo and it was working on gen 1. We can use experimentalStackMapping as stackMapping. It's working like a charm. I hope this will merge soon. Thanks for awesome solution @AnilMaktala

Edit: It's suppressing gen 2 cli sandbox or production limit error, but in the otherside it's giving limit error on Cloudformation, I added 200 Custom mapping to 15 different stack, it's still giving limit error on Cloudformation,

We have to declare ManyToMany fields manually on Gen 2, it's creating much resources compared to gen 1, But I did some much custom stack mapping still got no luck to fix limit error.

[MarlonJD]

PTAL, we need this

[loic-thomas]

I need this too.