[help] on better external player support

[Andy2244]

Working on better integration with external players (MX Player, Vimu). So hope this is the right place to get some help.

What is a good way to get the filename, filesize of a item? I found getPath, but cant find any size function in the BaseItemDto class?

PR #1719 now open and still looking for filesize, also looking if maybe we can support external subtitle streams like the normal Android client?