Try to restore support for exporting as PDF

[pcdavid]

When moving to Batik 1.14 (in GMF Runtime 1.14), support for exporting diagrams as PDF has been removed as it depends on Apache FOP, and that was not available in a compatible version in Orbit.
See org.eclipse.gmf.runtime.draw2d.ui.render.awt.internal.svg.SVGImageConverter.exportToPDF(SVGImage, OutputStream).

Recent versions of Tycho support getting dependencies directly from Maven Central without needing to go through Orbit, and the Eclipse Foundation's IP guidelines allow that. Maybe it's possible to restore support for PDF export by getting a compatible FOP from there.

[pcdavid]

For 1.16.2 which will move to Batik 1.17, see if we can restore this.