Well the best way is actually to do it manually, but trace bitmap is fast and can sometimes make good enough results
There are actually 2 tools in inkscape to trace bitmaps. Trace Pixmap is the other one. Both are very good.
This was already discussed and desired in 2011: https://forum.freecadweb.org/viewtopic.php?t=1778. In the meantime there seems to be a solution: https://www.phpbb.com/community/viewtop ... #p10754835, although I'm afraid you have to upload+submit+edit+copy_url_to_svg_tag. Furthermore there seems to be a loophole for uploading other stuff as well?