Attempt to handle DNL (Define Number of Lines) markers when parsing JPEG images (issue 8614)

Please refer to the specification, found at https://www.w3.org/Graphics/JPEG/itu-t81.pdf#page=49

Given how the JPEG decoder is currently implemented, we need to know the value of the scanLines parameter (among others) *before* parsing of the SOS (Start of Scan) data begins.
Hence the best solution I could come up with here, is to re-parse the image in the *hopefully* rare case of JPEG images that include a DNL (Define Number of Lines) marker.

Fixes 8614.

test/pdfs/issue8614.pdf.link

@@ -0,0 +1 @@
+https://github.com/mozilla/pdf.js/files/1125123/OBW-OVK.pdf

test/test_manifest.json

@@ -3194,6 +3194,14 @@
        "link": true,
        "type": "eq"
     },
+    {  "id": "issue8614",
+       "file": "pdfs/issue8614.pdf",
+       "md5": "7e8b66cf674ac2b79d6b267d0c6f2fa2",
+       "rounds": 1,
+       "link": true,
+       "lastPage": 1,
+       "type": "eq"
+    },
     {  "id": "bug1108753",
        "file": "pdfs/bug1108753.pdf",
        "md5": "a7aaf92d55b4602afb0ca3d75198b56b",