feat: Add new SetRelayServerData method to UnityTransport

[simon-lemay-unity]

This PR adds a new API to UnityTransport that allows setting the Relay server data directly from the RelayServerData structure provided by UTP. The idea behind this change is to make it easier for NGO users to benefit from new APIs introduced in UTP 1.3. These new APIs allow creating RelayServerData structures directly from allocation objects from the Relay SDK.

For example, given an allocation object coming directly from the Relay SDK, this PR allows configuring the Relay server data in this manner:

var serverData = new RelayServerData(allocation, "dtls");
transport.SetRelayServerData(serverData);

Compared to the previous ways of configuring the server data, this has many advantages:

• It's the same API for both client and host, since the RelayServerData constructors accept both Allocation and JoinAllocation objects.
• There's no need to deconstruct the Allocation/JoinAllocation objects in their individual fields just to pass them to NGO.
• There's no need to loop through the server endpoints in the allocation to find the one you want.
• There's no error possible where there's mismatch between the endpoint selected and the isSecure parameter of SetClientRelayData and SetHostRelayData (e.g. you can't select a DTLS endpoint and forget to set isSecure to true).
• It handles endpoints that are provided as hostnames instead of IP addresses (e.g. for secure WebSockets).
• It would transparently support IPv6 endpoints if the Relay server would start handing those out.

The previous APIs to set Relay server data remain available (and I'll get them to work with secure WebSockets in a future PR). Although if this lands I'll probably modify the Relay documentation to use the new ones.

Changelog

• Added: UnityTransport now provides a way to set the Relay server data directly from the RelayServerData structure (provided by the Unity Transport package) throuh its SetRelayServerData method. This allows making use of the new APIs in UTP 1.3 that simplify integration of the Relay SDK.

Testing and Documentation

• No tests have been added.
• No documentation changes or additions were necessary (maybe Relay documentation, but that can wait).

[SamuelBellomo]

Reading the description for this PR, this looks really cool. This will remove the should remove the need for our UnityRelayUtilities in boss room I believe. Will need to try.

[simon-lemay-unity]

Reading the description for this PR, this looks really cool. This will remove the should remove the need for our UnityRelayUtilities in boss room I believe. Will need to try.

Would be very curious to get some feedback once this is integrated in Boss Room. I've written the new APIs with the goal of simplifying integration with the Relay SDK. And while it did simplify our samples in UTP a lot, trying it in a real project like Boss Room will be interesting.

[johann-r-unity]

@ashwinimurt , this is the PR I was mentioning to add for NGO 1.1

[SamuelBellomo]

Reading the description for this PR, this looks really cool. This will remove the should remove the need for our UnityRelayUtilities in boss room I believe. Will need to try.

Would be very curious to get some feedback once this is integrated in Boss Room. I've written the new APIs with the goal of simplifying integration with the Relay SDK. And while it did simplify our samples in UTP a lot, trying it in a real project like Boss Room will be interesting.

@simon-lemay-unity I have a PR for NGO:1.1 update in boss room here Unity-Technologies/com.unity.multiplayer.samples.coop#708
I'll add this as a todo in there