feat: Splits Server in Core and Application (#1806)

> [!Note]
> **Developer Note**
> Now developers will only need to build/run the Application project instead of everything.
> When adding new projects, make sure to: 
> 1. Add a reference to that project in the Application project.
> 2. Add the dll file to the Distribution/Data/assemblies.json file

### Summary
- Adds an application project
- Consolidates process restarts to use `Core.Kill(true)`
- Removes some old messaging, for example processor optimization
- Fixes missing build cleanup

Projects/UOContent.Tests/Tests/Engines/Chat/Packets.cs

@@ -1,11 +1,11 @@
 using Server.Network;
 
-namespace Server.Engines.Chat
+namespace Server.Engines.Chat;
+
+public sealed class ChatMessagePacket : Packet
 {
-    public sealed class ChatMessagePacket : Packet
+    public ChatMessagePacket(string lang, int number, string param1, string param2) : base(0xB2)
     {
-        public ChatMessagePacket(string lang, int number, string param1, string param2) : base(0xB2)
-        {
             param1 ??= string.Empty;
             param2 ??= string.Empty;
 
@@ -25,5 +25,4 @@ namespace Server.Engines.Chat
             Stream.WriteBigUniNull(param1);
             Stream.WriteBigUniNull(param2);
         }
-    }
-}
+}