LibPDF: Add a test for inter-word spacing with TJ

Hand-written, based on the text example in Appendix G.2 in
the PDF 1.7 spec, with the xref table fixed up by `mutool clean`:

    mutool clean -dggg Tests/LibPDF/text.pdf Tests/LibPDF/text.pdf

Tests/LibPDF/text.pdf

@@ -0,0 +1,78 @@
+%PDF-1.3
+%µ¶
+
+1 0 obj
+<<
+  /Type /Catalog
+  /Pages 2 0 R
+>>
+endobj
+
+2 0 obj
+<<
+  /Type /Pages
+  /Kids [ 3 0 R ]
+  /Count 1
+>>
+endobj
+
+3 0 obj
+<<
+  /Type /Page
+  /Parent 2 0 R
+  /MediaBox [ 0 0 525 250 ]
+  /Contents 4 0 R
+  /Resources <<
+    /Font <<
+      /F1 5 0 R
+    >>
+  >>
+>>
+endobj
+
+4 0 obj
+<<
+  /Length 236
+>>
+stream
+BT
+/F1 24 Tf
+-30 TL
+40 40 Td
+[ (Hello) -2000 (World) ] TJ T*
+[ (Hello) -1000 -1000 (World) ] TJ T*
+[ (Hello) -1000 ] TJ [ -1000 ] TJ [ (World) ] TJ T*
+(should be the same on all lines:) '
+(The distance between "Hello" and "World") '
+ET
+
+endstream
+endobj
+
+5 0 obj
+<<
+  /Type /Font
+  /Subtype /Type1
+  /Name /F1
+  /BaseFont /Helvetica
+  /Encoding /MacRomanEncoding
+>>
+endobj
+
+xref
+0 6
+0000000000 65536 f 
+0000000016 00000 n 
+0000000070 00000 n 
+0000000136 00000 n 
+0000000291 00000 n 
+0000000581 00000 n 
+
+trailer
+<<
+  /Size 6
+  /Root 1 0 R
+>>
+startxref
+700
+%%EOF