Encapsulate nicegui.js

[falkoschindler]

As noticed by @nigelsim in #2984 (reply in thread), nicegui.js currently populates the global window scope, which can lead to conflicts with other JavaScript code like browser extensions.

Typically, I've see JS applications just encapsulate their own code inside a self executing block, so that this can't happen.

Even though I like the idea of wrapping nicegui.js in something like

(function() {

})();

we need to expose some of the functions like parseElements or createApp which are used in index.html.

Maybe we can implement nicegui.js as a module, exporting individual functions?

And maybe we can use bundlers like webpack or rollup to even further improve nicegui.js, e.g. by minifying the code or by bundling with Vue, Quasar and Tailwind?

Any help would be greatly appreciated, as this is not our primary area of expertise.

[nigelsim]

I've made a start here. A few manual tests and it looks fine, but I'm still figuring out the selenium tests before I put in a PR.

[nigelsim]

And another approach using JS modules, which I think is the better approach given NiceGUI is already using JS modules.