Expand VectorImage with wider span of features

The VectorImage is focused on supporting the static features of SVG Tiny 1.2, same as the original Qt Svg module.

Qt Svg is gradually getting support for more recent features however, without strictly adhering to a profile, but just based on the usefulness of these features.

To achieve parity, the same features should be supported in VectorImage, although a challenge here is that these can typically require off-screen rendering, which is less suitable for scenarios where you want to dynamically scale the contents. So the features have less relevance to the VectorImage use case, but either way it would be good to have some support for them.