Defer icons to icons stack to reduce DOM count

[indykoning]

This pr allows you to defer the content of SVG elements to drastically reduce DOM element counts for complex icons which are used often on a page.
It's an easier to use alternative to using spritesheets to tackle #185

The way it works is simply by adding an attribute of defer to the icon e.g.

<x-icon-camera defer />

And loading the stack at the bottom of your layout

   ...
    <svg hidden class="hidden">
        @stack('bladeicons')
    </svg>
</body>
</html>

As an example here we're using the larger SVGs of the heroicon pack multiple times

The transparent cubes are 1K and the dollar sign is 880B
Loading these in every time we use the icon on a page would result in nearly 6K added to the page which is a lot for a couple of icons.
A category page with products using that icon for it's price might add 24K to the document for 24 paginated products.
Defering these icons will leave that at 1K and only take a couple of bytes for using the icons

In the HTML this will now result in

This will not break any exising usages of the icon pack since it requires you to add the defer attribute manually or add it under attributes in config/blade-icons.php

[royduin]

@driesvints, do you have some time to review this? 😇

[driesvints]

Not yet I'm afraid :/

[royduin]

Np, take your time. Using the fork for now. Thanks 💯

[driesvints]

Heya sorry for the long wait. I like this @indykoning. Just got one question here for now. I'll hopefully can try this out soon.

[driesvints]

I didn't find time to actually try this out but since you two seem to have tested this already I'm going to merge and launch this. Thanks both 👍