[Feature Request] Preserve HTML, CSS, JS Intellisense in Vento language

[noelforte]

Context

Currently, the VSCode extension highlights CSS and JS correctly in VSCode, but does not yet provide Intellisense for them when used as embedded languages:

HTML

Vento

Proposed Solution

There are several extensions on the VSCode marketplace that preserve VSCode's built-in Intellisense/Language features for HTML and its embedded languages, notably [panoply/vscode-liquid](https://github.com/panoply/vscode-liquid, bmewburn/vscode-intelephense, withastro/language-tools, and andrejunges/vscode-handlebars, so it's definitely possible to do.

Possibly related to #5, since bringing baseline support for built-in markup may help with extending the highlighting engines for further embedded language formatting.

[oscarotero]

Yes, I'd love that.
TBH, I'm not an expert on VSCode plugins development and I remember to try that without luck.
I thought injectTo would make it possible, because it's the way to inject a grammar inside other, but seems that it needs something else.

I'll take a look to the plugins you've provided. Liquid example has a more complex configuration that probably allows that.

Any help with this is welcome.