Support SVG vector-effect as ´non-scaling-stroke`

[arnaud-secondlayer]

SVG paths with vector-effect="non-scaling-stroke" are not rendered properly.

From https://developer.mozilla.org/en-US/docs/Web/SVG/Attribute/vector-effect#setting_vector-effect_as_non-scaling-stroke
this is the expected rendering:

With dart_pdf, we're getting this rendering:

This is the source SVG, the last triangle has attribute vector-effect="non-scaling-stroke":

<svg viewBox="0 0 500 240">
  <!-- normal -->
  <path
    d="M10,20 L40,100 L39,200 z"
    stroke="black"
    stroke-width="2px"
    fill="none"></path>

  <!-- scaled -->
  <path
    transform="translate(100,0) scale(4,1)"
    d="M10,20 L40,100 L39,200 z"
    stroke="black"
    stroke-width="2px"
    fill="none"></path>

  <!-- fixed-->
  <path
    vector-effect="non-scaling-stroke"
    transform="translate(300, 0) scale(4, 1)"
    d="M10,20 L40,100 L39,200 z"
    stroke="black"
    stroke-width="2px"
    fill="none"></path>
</svg>