Allow owner and group properties of certificate_manage resource to be either String or Integer

[hrak]

Description

This PR ensures that owner and group properties of the certificate_manage resource can be either String or Integer, as is the case for all Chef internal resources.

Issues Resolved

List any existing issues this PR resolves

Check List

• [x] A summary of changes made is included in the CHANGELOG under ## Unreleased
• [ ] New functionality includes testing.
• [ ] New functionality has been documented in the README if applicable.