groupSvgElem = (elem) => {
  const dataStorage = svgCanvas.getDataStorage()
  const g = document.createElementNS(NS.SVG, 'g')
  elem.replaceWith(g)
  g.appendChild(elem)
  dataStorage.put(g, 'gsvg', elem)
  g.id = svgCanvas.getNextId()
}
Wrap an SVG element into a group element, mark the group as 'gsvg'.
@function module:svgcanvas.SvgCanvas#groupSvgElem
@param {Element} elem - SVG element to wrap
@returns {void}