api/stream/types: huge refactor & simplification of code

- created render() which handles ffmpeg & piping stuff
- merged remux() and merge() into one function
- simplified and cleaned up arguments
- removed headers since they're handled by internal streams now
- removed outdated arguments

api/src/stream/stream.js

@@ -13,8 +13,6 @@ export default async function(res, streamInfo) {
                 return await internalStream(streamInfo.data, res);
 
             case "merge":
-                return await stream.merge(streamInfo, res);
-
             case "remux":
             case "mute":
                 return await stream.remux(streamInfo, res);