react-core `SelectOption` should support label attribute

[kahboom]

For feature requests or enhancements, file an issue against patternfly-design.

SelectOption should behave like a typical option tag within a select element and allow you to specify a label for it. At the moment, it only supports a value.

A use case for needing this is dynamic fields that don't have a single label you can manually type in outside of the dropdown.

For bug reports, please provide as much relevant info as possible:

• What browser(s), device and OS experience the problem? Chrome, macOS Catalina
• Are you using a PatternFly JS framework implementation [1]? patternfly 4 / react-core
• What are the steps to reproduce the issue and what is the expected behavior?

Codepen here.

Tell us more about your product/project and timeline to help prioritize this issue.

• What product/project does this impact? Fuse Online, Syndesis

Related to https://github.com/syndesisio/syndesis/pull/7539