Make DLNA port configurable

[Conkuist]

Is your feature request related to a problem? Please describe.
XBVR DLNA Server can't run at the same time as Stash DLNA Server because both use the same port 1338

Describe the solution you'd like
Do not use the default port or make the port configurable
https://github.com/stashapp/stash/blob/develop/internal/dlna/service.go#L141

Describe alternatives you've considered
I tried to figure out how to change it myself inside the docker container but was unable to get it done.

Additional context
I run XBVR and Stash in Docker

[ipedrazas]

You cannot receive external multicast inside of a container (unless the network is set to host). These two issues explain the problem:

moby/moby#23659
moby/libnetwork#2397

Making the port configurable would allow to run the container using network_mode: host

[Conkuist]

DLNA only works when the network mode is set to host. This is true for XBVR and Stash. Both use the same port and none of them offer a way to change it. Which is the reason why I made the request to make it configurable.

[ipedrazas]

I've created a PR #4836 to enable the DLNA port conf from the config.yml file