wip: feat: React Slots a way for more natural JSX within Svelte

[jpinho]

context

This PR is still pretty much work in progress, but I can already share what this intends to achieve!
One thing missing on ReactAdapter is that strange feeling that you can't write JSX. Example:

  <ReactAdapter el={Badge} badgeContent={4} color="primary" />

With ReactSlots, I will enable you to write this instead:

  <ReactSlot {badgeContent}>
    {`
      <Badge badgeContent={badgeContent} color="primary"></Badge>
    `}
  </ReactSlot>

The only gotcha is that any React component used within a ReactSlot will have to be declared on context variable called ReactComponentsLibrary. This limitation comes from the library that makes ReactSlot possible: JsxParser from 'react-jsx-parser'. But aside from this ReactSlot makes React code inside of Svelte look much better and natural.

⭐ ⭐ If you would like to have this implemented faster, please share and upvote the PR. ⭐ ⭐