fix type mismatch, convert tabIndex string to number base 10

[mjaiswal-sfdc]

Fixes #

checkbox/index.js has tabIndex which is number but is assigned value props.tabIndex which is type string. This issue is potentially causing issue with checkbox focus in other projects where this module is consumed.

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[salesforce-cla]

Thanks for the contribution! It looks like @mjaiswal-sfdc is an internal user so signing the CLA is not required. However, we need to confirm this.

[mjaiswal-sfdc]

@interactivellama can you review this MR , this is the correct repo . Thanks!

[interactivellama]

Thank you for the contribution!

Could you send me a small demo on internal Slack on the issue this is fixing?

I'm curious to know why a number passed to a JSX HTML attributes that eventually is a string in HTML needs to be a number.

Is DataTable passing in the wrong type?

Feel free to re-iterate the existing component documentation to me.