Add round end Discord pings, discord webhook API (#19468)

Content.Server/Discord/WebhookEmbed.cs

@@ -0,0 +1,20 @@
+using System.Text.Json.Serialization;
+
+namespace Content.Server.Discord;
+
+// https://discord.com/developers/docs/resources/channel#embed-object-embed-structure
+public struct WebhookEmbed
+{
+    [JsonPropertyName("description")]
+    public string Description { get; set; } = "";
+
+    [JsonPropertyName("color")]
+    public int Color { get; set; } = 0;
+
+    [JsonPropertyName("footer")]
+    public WebhookEmbedFooter? Footer { get; set; } = null;
+
+    public WebhookEmbed()
+    {
+    }
+}