Migrate documentation demos to native HTML+JS

[sequba]

Description

We're facing many compatibility and interoperability issues using Codesandbox and Stackblitz. Since there seems to be no stable and robust alternative, it's time to self-host our demos.

We're aiming for:

• in the documentation we display a working demo natively (no iframe)
• there is no code displayed, only button "open in Stackblitz/Codesandbox"

Challenges:

• where to keep the demos? In separate repo (https://github.com/handsontable/hyperformula-demos) or inside the main repo (monorepo)
• in what form should we keep the demos - currently each demo is a npm project which requires building and bundling to run, but probably they could be converted to single-file form as they are relatively simple
• how to handle the framework demos (React, Angule, Vue, Svelte), which need to be kept as npm projects. Should they be still embedded in the docs as a Codesandbox iframe?

Links

• https://handsoncode.slack.com/archives/C031GBX62SE/p1723126003900819