[Toolkit][Shadcn] Add Spinner component

[bernard-ng]

Q	A
Bug fix?	no
New feature?	yes
Deprecations?	no
Documentation?	no
License	MIT

Add Spinner component, An indicator that can be used to show a loading state.
refs: https://ui.shadcn.com/docs/components/spinner

[Kocal]

Thanks for the contribution, that's much appreciated!

I've pushed on your PR some modifications:

• it was not possible to use <twig:Spinner class="...">, the class attribute was fully overridden by {{ ...attributes }} (looks like the ComponentAttributes::getIterator() does not handle ComponentAttributes::$rendered property, like ComponentAttributes::__toString()) and so the Spinner was not rotating anymore. Using {{ ...attributes.without('class') }} fixed the issue
• I added some examples with size and color

[Kocal]

Thank you @bernard-ng.