Add network discovery

[Jenna1337]

Add support for Simple Service Discovery Protocol, and Universal Plug and Play.

Don't forget to add settings to enable/disable them as well.

[Jenna1337]

Note: a custom multicast protocol might work better, since SSDP and UPnP seem fairly complex and over-engineered.
All it needs to do is advertise its IP address, port, and text identifying what service it is. A simple text JSON format would suffice.

[Jenna1337]

See https://www.iana.org/assignments/multicast-addresses/multicast-addresses.xhtml

[Jenna1337]

See also: https://datatracker.ietf.org/doc/html/rfc2365
Note: https://www.cisco.com/c/dam/en/us/support/docs/ip/ip-multicast/ipmlt_wp.pdf
says "avoid the 239.0.0.0/24 and 239.128.0.0/24 subranges", referencing rfc2365. We should use a different multicast address, but the address we current have should also work.

[Jenna1337]

Seems the 239.0.0.0/24 and 239.128.0.0/24 subranges are used on most layer 2 switches for mapping to MAC addresses. Using an address in that range could pose an issue at some point.

[Jenna1337]

It seems we should use either an address in the range 224.0.0.0 - 224.0.0.255 or 239.255.0.0/16

Optimally we'd use an IP in the 224.0.0.0 - 224.0.0.255 range, but these are reserved as per https://www.iana.org/assignments/multicast-addresses/multicast-addresses.xhtml#multicast-addresses-1

We could apply for a multicast address in this range, or use an address in the 239.255.0.0/16 range.

[Jenna1337]

I forgot to reference this issue in the commit, but 4dd75fb added classes for network discovery

[Jenna1337]

Welp, the server sends the data to the multicast address, but the client doesn't seem to be receiving the data for some reason, and I cannot figure out why. Requesting additional help.

[Jenna1337]

Ok, so it turns out I was testing the wrong version, which is why I wasn't noticing any changes. Anyways, server discovery technically works now, but it's pretty rudimentary and honestly could be way better and not as jank. I'd like to make it so multiple clients on the same device can see the server discovery, but idk how to do that, seeing how C# needs multicast to be bound to the same port it's reading from. Also rn the code is using UDP port 1900, which is reserved for UPnP, but we're sending INI data over it.