Add custom Rich Presence names

[JustArion]

Discord normally discards the Name property and replaces it with the name associated with the Discord Application. Projects such as arRPC from OpenAsar are more lenient on such restrictions. Clients using OpenAsar will have their Discord Rich Presence shown like the screenshot below if the commit is merged.

Normal Discord clients are unaffected by this change and modifying the property will do nothing for them (for now).

If the user has a normal Discord client:

Confirmed working with arRPC via the BasicExample

            client.SetPresence(new RichPresence()
            {
                Name = "A test Example",
                Details = "A Basic Example",
                State = "In Game",
                Timestamps = Timestamps.FromTimeSpan(10),
                Buttons = new Button[]
                {
                    new Button() { Label = "Fish", Url = "https://lachee.dev/" }
                }
            });

Client running openAsar:

The PR is similar to #255 though currently only targets openAsar users. Discord will probably allow this in the default client in the future.

Fixes #48

[Lachee]

Hello,

Thank you for your awesome contributions.
However as this isn't officially supported by Discord yet, I do not wish to accept this PR. I worry having the ability to set a name will confuse a lot of users of the library and seem like non-functioning code because it requires a custom client to view.

Feel free to maintain your fork specifically for custom clients.