Tests: Add a type3 test pdf
A manual test, but better than nothing.
I hand-wrote the file, and used mutool to fix up xref and stream
lengths:
mutool clean Tests/LibPDF/type3.pdf Tests/LibPDF/type3.pdf
The file contains one `d1` character which per spec shouldn't
contain color statements, and if it does it should be ignored,
and one `d0` character which can contain color.
The text then sets a color before rendering the text.
Per spec, the text color should affect the `d1` character but
not the `d0` one. We get this wrong, but so does Preview.app.
(PDFium gets it right.)
But independent of the colors, just rendering the glyphs at all
at the right position is already good :^)
Nico Weber