filename pattern customization

- added metadata for rutube and vimeo.
- added a picker for preferred filename pattern.
- fixed content disposition header.
- mute and audio dub tags don't appear together in a file name anymore.
- youtube: dub file name tag doesn't appear anymore if audio track is default.

package.json

@@ -24,6 +24,7 @@
     },
     "homepage": "https://github.com/wukko/cobalt#readme",
     "dependencies": {
+        "content-disposition-header": "^0.6.0",
         "cors": "^2.8.5",
         "dotenv": "^16.0.1",
         "esbuild": "^0.14.51",