Add transformer.js support

[Stevenic]

Any takers? Now that we cna run in a browser if we add transforfer.js support for generating embeddings, we can run completely offline in a browser

[yencolon]

I've made some progress and got it working. I still need a bit of time to test it out, so I'll take this enhancement.

[yencolon]

Hugging Face support PR is now live on the browser-support branch. @Stevenic, it's ready for review.

[Stevenic]

Sorry @yencolon I've been swamped again at Microsoft but I merged your PR and will publish new bits tomorrow