Propose Icon styles

[torchiaf]

We currently have a unique style for each icon, but many other libraries implement different shapes for each icon type like Solid, Regular, etc. https://fontawesome.com/icons
It would be great to have something similar for Rancher Products; it would allow developers to create UI elements, like buttons, using different styles of icons depending on the context where they are used.
For example we could implement a Secondary style and use it in case we want to create secondary buttons, as we did for the Help button #3483