api: initial subtitles functionality with youtube support

this took way more effort than i expected it to do, mostly because of youtube locking everything down to shit

local processing doesn't function with subtitles yet, wasm needs to be updated

api/src/processing/match-action.js

@@ -31,7 +31,8 @@ export default function({
                     createFilename(r.filenameAttributes, filenameStyle, isAudioOnly, isAudioMuted) : r.filename,
             fileMetadata: !disableMetadata ? r.fileMetadata : false,
             requestIP,
-            originalRequest: r.originalRequest
+            originalRequest: r.originalRequest,
+            subtitles: r.subtitles,
         },
         params = {};