Export node type guards

[nikolapantic-inter]

Hello 👋

I have found that this library has some nice type guards in source code that are never exposed to consumers. Sure, I could dig them out in the ESM structure but then building/bundling/testing will become a pain. Additionally they are not exported in the UMD bundle.

Kindly requesting to have all type guards exposed. I'll go on about trying to contribute with this myself 👍🏻