Add support for SVG images

SWT currently loads icons exclusively as raster graphics (e.g., PNGs)
without support for vector formats like SVG (except for Linux). A major
drawback of raster graphics is their inability to scale without
degrading image quality. Additionally, generating icons of different
sizes requires manually rasterization of SVGs as a preparatory step,
leading to unnecessary effort and many icon files.

This change introduces support for vector graphics in images, enabling
SVGs to be used for images. An SVG rasterizer can be provided via an SWT
fragment. This change adds an according fragment based on the JSVG
library. An according FileFormat implementation is added, which utilized
a present SVG rasterization fragment to rasterize images for the desired
zoom factor.

Fixes eclipse-platform#1438

Author: Michael5601

tests/org.eclipse.swt.tests/META-INF/p2.inf

@@ -0,0 +1,4 @@
+# pull in the applicable implementation fragment at build time (bug 461427)
+requires.0.namespace = org.eclipse.equinox.p2.iu
+requires.0.name = org.eclipse.swt.svg
+requires.0.range = 0.0.0