Replace fem-post-filter-data-at-point PNGicon

Currently a FEM WB tool has a PNG icon in FreeCAD. This file is the
fem-post-filter-data-at-point.png The rest of the icons in FEM WB 
are SVG files. This PNG icon is from ParaView and it has a different
stile, compared with the other FEM icons. It would be good to have 
an original SVG icon for this tool.

This commit replaces the PNG file with a SVG file with a new design. 
This job was a request from the FEM WB developer, in the UX/UI Design
FreeCAD Forum.

The new SVG icon follows the FreeCAD Artwork Guidelines
- https://www.freecadweb.org/wiki/Artwork_Guidelines

The new design keep the stile of the other icons with similar function 
in the FEM toolbar
- https://www.freecadweb.org/wiki/File:Fem-DataAlongLine.svg