Add support for TrueType Collection fonts (issue 9262)

The specification can be found at https://www.microsoft.com/typography/otspec/otff.htm, under the "Font Collections" heading.

Fixes 9262.

test/pdfs/.gitignore

@@ -65,6 +65,7 @@
 !issue8823.pdf
 !issue9084.pdf
 !issue9105_reduced.pdf
+!issue9262_reduced.pdf
 !issue9291.pdf
 !bad-PageLabels.pdf
 !decodeACSuccessive.pdf

test/test_manifest.json

@@ -734,6 +734,13 @@
        "lastPage": 1,
        "type": "eq"
     },
+    {  "id": "issue9262",
+       "file": "pdfs/issue9262_reduced.pdf",
+       "md5": "5347ce2d7b3866625c22e115fd90e0de",
+       "rounds": 1,
+       "link": false,
+       "type": "eq"
+    },
     {  "id": "issue8707",
        "file": "pdfs/issue8707.pdf",
        "md5": "d3dc670adde9ec9fb82c974027033029",