Add duotone support

[ingeniumed]

Since we have verified that duotone support is not there, this has been made to add that in. What needs to be done is that, CSS has to be injected onto the page to get duotone values as styles that can be applied.

[ingeniumed]

I experimented with this more and it turns out there's an SVG mask that's required. Injecting this along with the CSS properties didn't really get it to work. I verified in Duotone.js if it was picking up these properties and that wasn't the case.

The blockname is not passed in which means it's not block specific, which is something we would need to add support for. For now, this is going to be set aside for the initial launch.