Add class="feather" attribute to SVG elements

[aecio]

Adding the class "feather" to SVG elements would make it easier to apply CSS styles to icons.

Following is an example an SVG element that include a CSS class from https://feathericons.com:

<svg class="feather feather-activity sc-dnqmqq jxshSx" xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true" data-reactid="36"><polyline points="22 12 18 12 15 21 9 3 6 12 2 12"></polyline></svg>

[CorradoSurmanowicz]

Please merge the pull request. This is critical for proper use IMHO.