Keep <svg> at the root of the structure

[tauthomas01]

Issue

Some of the newest icon requests contain markups that are not needed at the root of the SVG file.

Examples

Reference example Reference example

This is mostly due to SVG icons generated by vector applications such as Illustrator that keep its original layers.

Proposed solution

We should have a test that rejects any markups at the root except the <svg> to keep the SVG lightweight and clean.