feat: adds extension for solid-js

[thedanchez]

Seeing as g6-extension-react exists, I decided to spend some time to add g6-extension-solid.

SolidJS is a JSX library that allows you to create incredibly performant UIs.

It has the following points:

• Does not use a virtual DOM (VDOM)
• Renders only once (no re-renders like React)
• Uses fine-grained reactivity to track changes and apply highly performant updates

I believe Solid is a superior library to React and much easier to maintain (as you can see from the core implementation).

There is still more to do to finish this but I wanted to push up the draft PR to get a sense if this would be okay to add as part of G6?

If not, happy to publish it under my own scope separately.

[Aarebecca]

@thedanchez Great work! We're excited to see contributions from the open-source community. I suggest you publish it under your own scope with the name g6-extension-solid, for example: thedanchez/g6-extension-solid. We'll feature it on the official G6 website.