[Feature Request] Implement Service Worker to speed up semantic search

[WilliamJWen]

Is your feature request related to a problem? Please describe.
Using the semantic search bar for the first time is sometimes slow, which may be due to fetching the transfomer.js model through CDN.

Describe the solution you'd like
A Service Worker is a script that runs in the background of a web browser, separate from the web page, and provides capabilities that don't require a web page or user interaction. It acts as a network proxy, intercepting and handling network requests, including the ability to serve cached content, enabling offline functionality, and controlling how resources are fetched.

This allows more control to cache resources like the Model and pre-computed Embeddings and may even provide offline access to the semantic search bar.

Describe alternatives you've considered (Optional)
An alternative is to have a javascript as part of the html that's available on all pages(for example, the left side nav bar) to load/fetch the transformer models and embeddings and so on, whenever any page under learningc.org is opened