Add features: createRoot, PromiseWrapper, and react lazy

[evbo]

Hi,

I am very short on time and had to "throw this over the wall" but here are 3 very important React features I'm using for my own needs:

1. createRoot is the new alternative to ReactDOM.render and if not used will limit React features to version 16
2. PromiseWrapper is a convenient helper utility to use Suspense for experimental data fetching from any arbitrary source
   • Here's a great article about this pattern
3. React Lazy lets you lazy load modules for Suspense

A lot of testing is needed and code cleanup. I am hoping the Slinky community is patient with these WIP changes and is willing to help out a bit too. I will try to support more in time but I wanted to initiate the PR just to get the ball rolling with at least baseline functionality.

Thanks!

[evbo]

addresses: #196

[shadaj]

Thanks for the PR @evbo! This will be a great starting point for getting Slinky up to speed with the latest React features.

In the near future, would you be able to fix some of the formatting issues? That way we can get this merged and start working on followup testing.

[DamianReeves]

Wondering what needs to be done to get this in

[evbo]

this shouldn't be private as I'm finding often non-presentational logic may want to check the existence of data without triggering unnecessary exceptions to be thrown

[evbo]

Wondering what needs to be done to get this in

I pretty much just threw the code over the wall, missing some unit testing opportunities, code cleanliness here and there. I left a comment with the only functional change I would still make.