Fix SVG sequence file loading
    
    This PR fixes an issue when trying to load an SVG file sequence.
    
    Modified it so SVG files are treated as Vector Images instead of Vector
    Levels, which allows the SVG files to be detected as a single image file
    or a series of files (filename.####.svg or filename_####.svg format).
    
    Ported from https://github.com/tahoma2d/tahoma2d/pull/1212
    
    Co-Authored-By: manongjohn <19245851+manongjohn@users.noreply.github.com>