constructor({ docId, ownerDocument = globalThis.document }) {
    super();
    this.#docId = docId;
    this.#document = ownerDocument;
  }
FilterFactory aims to create some SVG filters we can use when drawing an
image (or whatever) on a canvas.
Filters aren't applied with ctx.putImageData because it just overwrites the
underlying pixels.
With these filters, it's possible for example to apply some transfer maps on
an image without the need to apply them on the pixel arrays: the renderer
does the magic for us.