Add a script to check components are being exported as named exports

[janechu]

Previous Behavior

No check to see if components are exported in the package.json.

New Behavior

This new script checks that components are being exported.

[fabricteam]

📊 Bundle size report

_{🤖 This report was generated against 3287714774098eb5f902d9110a214033807d5e34}

[codesandbox-ci[bot]]

This pull request is automatically built and testable in CodeSandbox.

To see build info of the built libraries, click here or the icon next to each commit SHA.

[JustSlone]

@janechu closing as that is the only way to stop notifying reviewers. Please update your PR to point to master following this guide: https://github.com/microsoft/fluentui/pull/31361 and reopen when it's updated. Thanks!