SkPDF: Fix Type3 ToUnicode table.

This seems to fix text extraction on Adobe Reader

  - Registry/Ordering is now set to Skia/SkiaOrdering.
  - Type3 fonts now get a FontDescriptor (force symbolic font).
  - CMapName is now Skia-Identity-SkiaOrdering
  - CMap behaves correctly for single-byte fonts.

Also:
  - SkTestTypeface returns tounicode map for testing.
  - Unit test updated

All PDFs render the same

BUG=skia:5606
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2292303004

Review-Url: https://codereview.chromium.org/2292303004
diff --git a/tests/PDFGlyphsToUnicodeTest.cpp b/tests/PDFGlyphsToUnicodeTest.cpp
index d83ce66..3ba8870 100644
--- a/tests/PDFGlyphsToUnicodeTest.cpp
+++ b/tests/PDFGlyphsToUnicodeTest.cpp
@@ -125,11 +125,11 @@
 
     char expectedResultSingleBytes[] =
 "2 beginbfchar\n\
-<0001> <0000>\n\
-<0002> <0000>\n\
+<01> <0000>\n\
+<02> <0000>\n\
 endbfchar\n\
 1 beginbfrange\n\
-<0003> <0006> <1010>\n\
+<03> <06> <1010>\n\
 endbfrange\n";
 
     REPORTER_ASSERT(reporter, stream_equals(buffer, 0,