refactor: convert redundant new TypeName() to target-typed new()

Replace explicit constructor calls with target-typed new() expressions
where the type is already specified on the left side of the assignment.
This is a C# 9+ feature that reduces redundancy.

Files changed:
- Container.cs: field assignments in constructors
- EntityPalette18/112/113.cs: static field initializers
- ChatParser.cs: StringBuilder local variable
- Movement.cs: field assignments in constructor
- PacketPalette18.cs: field initializers
- EnchantmentMapping.cs: field reassignments

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

MinecraftClient/Protocol/Message/ChatParser.cs

@@ -511,7 +511,7 @@ namespace MinecraftClient.Protocol.Message
 
             string message = string.Empty;
             string colorCode = string.Empty;
-            StringBuilder extraBuilder = new StringBuilder();
+            StringBuilder extraBuilder = new();
             foreach (var kvp in nbt)
             {
                 string key = kvp.Key;