SVG image transformer

[RicLeP]

Added an SVG image field and transformer for Storyblok assets.

The old transformer could break if you were using mixed raster and SVG images with transformations in your templates.

By default, when encountering an SVG image the field class will now be Riclep\Storyblok\Fields\SvgImage and use the Riclep\Storyblok\Support\ImageTransformers\StoryblokSvg transformer.

The new field and transformer will return the unaltered SVG path from Storyblok without attempting to transform it. There are plans to possibly expend this in the future with SVG specific functionality.

You can restore the original behaviour by creating a field class in app\Storyblok\Fields. The class name should match with the FieldName or BlockNameFieldName. E.g. App\Storyblok\Fields\Logo or App\Storyblok\Fields\HeroBlockImage