[META] Rewrite gst-web HTML5 interface frontend

[ehfd]

Meta-issue for various HTML5 interface problems and enhancements.

Includes: #9, #22, #25, #39, #74, #76, #98, #107, #159.

Such issues should be addressed holistically because the versions of various JavaScript libraries (including guacamole-keyboard and Vue) that we use are outdated and require updates.

Upgrading Vuetify is fine for now if it's more trivial, but #159 is a key performance issue that arises from reactive DOM updates.

I thought reactive UI libraries were the way to go, but not necessarily now, especially regarding low-power or embedded clients.

Moreover, using a reverse proxy like nginx, Caddy or even socat will guarantee an increase in loading speed, and Vue should be compiled using npm.

My standards for the new web interface:

1. The framework doesn't eat up the web browser CPU thread from DOM updates and renders and is generally zero-CPU-emission (unlike Vue).
2. The framework does not suddenly lose API compatibility with a new "version" that is actually a completely new framework and deprecates the security support for the one before (again unlike Vue).
3. Prefer keeping the web code short using a framework (at the potential risk of it being out of security support) rather than not using a framework and accumulating a massive code footprint.

Ideal interface examples:

[maxpain]

Any updates?

[ehfd]

Currently discussed in #85

[ehfd]

I could really receive help from someone who could update the breaking web interface. Old Vue and Vuetify are breaking a lot of capabilities. Basically a 2019-era antique.

[ehfd]

Also: https://gsap.com/resources/fouc/

Layout was forced before the page was fully loaded. If stylesheets are not yet loaded this may cause a flash of unstyled content.

Edit: this is fixed in #156.

[ehfd]

Courtesy of @ayunami2000 :

test.zip

This is an example prototype that does not use any UI framework. People are welcome to carry over from here.