[3.2.0-beta3] Kodi's UPNP server is not detected unless you start Kodi while viewing VLC's local network section

This is not a huge problem but any detection fixing is worthwhile.

First of all, I'm not sure if many people know this, but Kodi has a UPNP server built-in. You can enable it by going to Kodi's settings > Services > UPNP > and enable "UPNP support" and "share my libraries"

Here's the steps to reproduce.

1. Run Kodi with its UPNP server enabled on the local network. (every other software and device on my network can see it, including my Samsung smart TV)
2. Open VLC 3.2.0 beta 3, and go to local network.
3. Kodi isn't listed at all on the available shares list in the local network section.
4. Close Kodi and restart Kodi with the UPNP server enabled.
5. Kodi magically pops up in VLC's local network section!
6. Go back to the VLC home menu.
7. Go to VLC's local network section. Kodi is once again missing from the list of available shares!
8. Closing and restarting Kodi makes it show up again while you're looking at VLC's local network section.

Expected result: Kodi should already be in the local network section's list of available results when Kodi is running.

Actual result: VLC can't see Kodi's UPNP sharing unless you start Kodi while looking at the local network section.

Hopefully, fixing this will improve overall UPNP detection robustness.