Implement game rule configs. Game rules are now proper prototypes instead of just an alias for a system. (#8539)

Content.Server/GameTicking/Rules/Configurations/InactivityGameRuleConfiguration.cs

@@ -0,0 +1,17 @@
+using JetBrains.Annotations;
+
+namespace Content.Server.GameTicking.Rules.Configurations;
+
+/// <summary>
+/// Configures the <see cref="InactivityTimeRestartRuleSystem"/> game rule.
+/// </summary>
+[UsedImplicitly]
+public sealed class InactivityGameRuleConfiguration : GameRuleConfiguration
+{
+    public override string Id => "InactivityTimeRestart"; // The value for this in the system isn't static and can't be made static. RIP.
+
+    [DataField("inactivityMaxTime", required: true)]
+    public TimeSpan InactivityMaxTime { get; }
+    [DataField("roundEndDelay", required: true)]
+    public TimeSpan RoundEndDelay { get; }
+}