Merge pull request #7550 from Snuffleupagus/Type1-toUnicode-builtInEncoding-fallback

For embedded Type1 fonts without included `ToUnicode`/`Encoding` data, attempt to improve text selection by using the `builtInEncoding` to amend the `toUnicode` map (issue 6901, issue 7182, issue 7217, bug 917796, bug 1242142)

test/pdfs/.gitignore

@@ -22,6 +22,7 @@
 !issue5808.pdf
 !issue6204.pdf
 !issue6782.pdf
+!issue6901.pdf
 !issue6961.pdf
 !issue6962.pdf
 !issue7020.pdf

test/test_manifest.json

@@ -1220,6 +1220,20 @@
        "link": false,
        "type": "text"
     },
+    {  "id": "issue6901-eq",
+       "file": "pdfs/issue6901.pdf",
+       "md5": "1a0604b1a7a3aaf2162b425a9a84230b",
+       "rounds": 1,
+       "link": false,
+       "type": "eq"
+    },
+    {  "id": "issue6901-text",
+       "file": "pdfs/issue6901.pdf",
+       "md5": "1a0604b1a7a3aaf2162b425a9a84230b",
+       "rounds": 1,
+       "link": false,
+       "type": "text"
+    },
     {  "id": "issue6962",
        "file": "pdfs/issue6962.pdf",
        "md5": "d40e871ecca68baf93114bd28c782148",