Prevent storybook from mutating the built package contents

[rajsite]

🧹 Tech Debt

Currently storybook's build creates a duplicate copy of the typescript type files in nimble components.

See how in the following package there is the typescript build output:
https://unpkg.com/browse/@ni/nimble-components@9.0.4/dist/esm/

And inside the typescript build output there is a duplicate of the typescript d.ts type files in the folder nimble-components:
https://unpkg.com/browse/@ni/nimble-components@9.0.4/dist/esm/nimble-components/src/

Those files were excluded in #567 in a gitignore but we should find out how to prevent storybook from mutating that folder.

[rajsite]

This regressed and had to be resolved again: #1558

Still haven't thought of a great way to prevent the regression. One thought was storybook should be in it's own package (so that it could rely on a nimble-react package generated from nimble-components). If that happened this would be resolved since stroybook wouldn't be directly involved in the components build.

[rajsite]

Closing in favor of #1747 which gives a way to manually validate (though open to other ideas)