Navigation leverage icon core API

This MR is currently made of 2 parts:

• Everything inside /core/asset , /core/lib and /core/tests is a duplicate of 📌 Navigation leverage icon core API Needs work which was taken as a starting point. OF course, this part will be removed when the other issue is merged into 11.x
• the changes in /core/modules/navigation is the interesting part for this issue

Thank you for great start. I see some bem mistakes. Gonna fix it.

I don't think we should define viewbox somewhere

I don't think we should define viewbox somewhere

It depends of the icon pack we are implementing. Th goal of this Icon API is to provide simple tools to faithfully implement the icon packs as documented upstream by the icons provider.

For example, Bootstrap Icons expects a viewBox, so we need to deal with it:

<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-emoji-heart-eyes" viewBox="0 0 16 16">
  <path d="M8 15A7 7 0 1 1 8 1a7 7 0 0 1 0 14zm0 1A8 8 0 1 0 8 0a8 8 0 0 0 0 16z"/>
  <path d="M11.315 10.014a.5.5 0 0 1 .548.736A4.498 4.498 0 0 1 7.965 13a4.498 4.498"/>
</svg>

In navigation module, we are both the icons provider and the icon pack definition author. So, we can do anything. If it works OK without the viewBox attribute, and you think it will be better without it, we can remove it.

I think we should keep the original viewBox attribute if it is not reassigned by the template

Here I added a simple illustration of how the absence of the original attribute breaks the adaptability of icons.

https://codepen.io/finnsky/pen/jOgKdWz

I will add the viewbox available as a variable if set in the svg, this will match your needs and be an optional feature when people need it.

I will update here when pushed on the main MR.

@mogtofu33 thank you for this and for all that initiative