[Spike] react-icons: investigate internal icon set flexibility

[kmcfaul]

We need to have a mechanism to allow our internal icons to be changed between our current PF icons and the RHDS icons. This should be separate from the unified theme as we want to allow separate adoption/usage outside of the theme.

Possible approaches:

• App level context, similar to animation opt-in. Requires extra code for every icon usage.
• Top-level css class. In practice this would play out similarly to the context.
• Updating our react-icons generated components to do either of these checks internally and serve either icon from the same PF icon component. Benefit being no extra code in the react repo but needs investigation into how our icons are generated. Needs to also investigate performance if each icon runs the check too much (or renders both icons and we use css flags to show/hide specific icon set).