Specular Workflow Support

[Void-Paw]

Describe what are you aiming to achieve
I would like the ability to utilize the specular workflow with these shaders such that I can leverage the full potential of our specular maps. By supporting specular maps, artists can have much tighter control over the reflections any kind of surface gives off and lets them intentionally decouple the specular color from the diffuse color to achieve unique effects that you can't achieve with the metallic workflow.

Describe any workarounds you can use now
There are ways to convert from specular to metallic workflows (as documented in this marmoset article), but in doing so there is often a loss of fidelity and an increase in artifacts.

Any other comments or context/references
This topic was brought up in Orels' discord server and the relevant discussion can be seen here.