Tweak adjustType1ToUnicode for fonts with a predefined *named* encoding (bug 1811668, PR 14050 follow-up)

*Please note:* I cannot reproduce the problem reported in bug 1811668, regarding the context menu, and in any case it's not clear that that part is even a PDF Viewer bug.

Looking at bug 1811668 I couldn't help but noticing that the textLayer isn't correct, and it's unfortunately once again a problem with the `adjustType1ToUnicode` function. That's intended to help improve text-selection for fonts without a /ToUnicode-entry, and in many cases it does help (the original PR fixed lots of issues) however it's also caused some problems.

In order to improve text-selection in bug 1811668, we'll now properly ignore fonts that have a predefined *named* encoding specified since that's really the intention with PR 14050.

test/pdfs/.gitignore

@@ -399,6 +399,7 @@
 !issue4461.pdf
 !issue4573.pdf
 !issue4722.pdf
+!bug1811668_reduced.pdf
 !issue4800.pdf
 !issue9243.pdf
 !issue13147.pdf

test/test_manifest.json

@@ -1006,6 +1006,12 @@
        "lastPage": 1,
        "type": "eq"
     },
+    {  "id": "bug1811668",
+       "file": "pdfs/bug1811668_reduced.pdf",
+       "md5": "87aa65d89aa0682cbe7b87152b884495",
+       "rounds": 1,
+       "type": "text"
+    },
     {  "id": "issue8092",
        "file": "pdfs/issue8092.pdf",
        "md5": "e4f3376b35fd132580246c3db1fbd738",