Add accordion component

[alexander-schranz]

Accordion is build on top of the aria attributes by the w3c example:
https://www.w3.org/TR/wai-aria-practices-1.1/examples/accordion/accordion.html

<div id="accordion">
    <section class="collapse">
        <h4>
            <button id="accordion-button-1" aria-expanded="false" aria-controls="accordion-body-1">
                Header 1
            </button>
        </h4>

        <div id="accordion-body-1" aria-hidden="true" aria-labelledby="accordion-button-1">
            Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut
            labore et dolore magna aliquyam erat, sed diam voluptua.
        </div>
    </section>

    <section class="collapse">
        <h4>
            <button id="accordion-button-2" aria-expanded="false" aria-controls="accordion-body-2">
                Header 2
            </button>
        </h4>

        <div id="accordion-body-2" aria-hidden="true" aria-labelledby="accordion-button-2">
            Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut
            labore et dolore magna aliquyam erat, sed diam voluptua.
        </div>
    </section>
</div>

import Accordion from '@sulu/web/packages/components/accordion/accordion';
var component = new Accordion();
component.initialize(document.getElementById('accordion'), {});

https://jsfiddle.net/26gj8mdh/1/

@luca-rath did on top of your implementation created the accordion here. Adjusted to remove the data classes and build it on top of the aria attributes, so less need to be written by the developer which use the component. Also jquery is removed as I not longer want to build components here on top of jquery, so websites build are smaller. So we maybe could remove in the project jquery or lazy load it where required.

[luca-rath]

Code looks good, will try it in a project next week

[luca-rath]

Code looks good, will try it in a project next week

Just tested using the jsfiddle, looks good, therefore I'm going to merge it now