Merge pull request #2808 from q--/Detect_PDF.js_version

Add new ways to detect PDF.js and its version

src/apps.json

@@ -8028,8 +8028,12 @@
       "html": "<\\/div>\\s*<!-- outerContainer -->\\s*<div\\s*id=\"printContainer\"><\\/div>",
       "icon": "PDF.js.svg",
       "js": {
+        "_pdfjsCompatibilityChecked": "",
         "PDFJS": "",
-        "PDFJS.version": "^(.+)$\\;version:\\1"
+        "PDFJS.version": "^(.+)$\\;version:\\1",
+        "pdfjsLib.version": "^(.+)$\\;version:\\1",
+        "pdfjs-dist/build/pdf.version": "^(.+)$\\;version:\\1",
+        "pdfjsDistBuildPdf.version": "^(.+)$\\;version:\\1"
       },
       "url": "/web/viewer\\.html?file=[^&]\\.pdf",
       "website": "https://mozilla.github.io/pdf.js/"