[Do not review] Allowing selectionzone to accept a classname

[nebhatna]

Pull request checklist

• Addresses an existing issue: Fixes #0000
• Include a change request file using $ yarn change

Description of changes

(give an overview)

Focus areas to test

(optional)

[msft-github-bot]

Thanks for submitting this change, but due to work currently in progress to prepare master for our version 8 beta release, we're asking contributors to either wait a couple weeks to submit changes (if it's not urgent) or submit to the new 7.0 branch (if it's urgent). See #15222 for more details. Thank you for your contribution and understanding!

[nebhatna]

Just created a PR for tracking purpose so i dont lose these changes. Please do not review yet, i will not be merging till the fluent freeze is over.

[codesandbox-ci]

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Sandbox	Source
Fluent UI Button	Configuration
microsoft/fluentui: codesandbox-react-template	Configuration
microsoft/fluentui: codesandbox-react-next-template	Configuration
microsoft/fluentui: codesandbox-react-northstar-template	Configuration

[elisabethcvs]

Looks good to me