Allow SVG uploads in widget (svg_image compatibility)

Patch at #2 could not apply in version 2.4, here is an updated version.

This creates a hard dependencies on another contrib module so it's unlikely to be considered for inclusion.

It would be better to detect if the other module is present and conditionally add support. Also, there are a few different SVG image modules.

I have added the condition to skip the SVG image file validate for the Image Widget Crop Entity Form Display. and it is working fine for me.

You need patch 2 or3 plus 5 in order to fix the problem.

But I'm agree that this dependency is no a good solution.

As I understand it, SvgImageWidget overrides ImageWidget through the svg_image_field_widget_info_alter hook.
Its formElement method adds the svg extensions in $element['#upload_validators']['file_validate_extensions'][0]

But ImageCropWidget is not aware of this and implement ImageWidget removing the svg override...

Maybe it should be the svg_image module that alter the file_validate_extensions though another way (hook) ?

The patch from #3 does not work with svg_image 3.1.0. Here is an adjusted patch.