Rewrite the C++ Demangler (#416)

* Rewrite the C++ Demangler

This new Demangler provides support to almost every possible mangled
symbols and should behaves like GNU c++filt.

It works on 98.9% of the sdk's symbols and 99.5%
of Puyo Puyo Tetris's symbols.

* Fix code style

* Fix noexcept enclosed expression parsing issues

* fix code style issues

Ryujinx.HLE/HOS/Diagnostics/Demangler/Ast/NestedName.cs

@@ -0,0 +1,26 @@
+using System.IO;
+
+namespace Ryujinx.HLE.HOS.Diagnostics.Demangler.Ast
+{
+    public class NestedName : ParentNode
+    {
+        private BaseNode Name;
+
+        public NestedName(BaseNode Name, BaseNode Type) : base(NodeType.NestedName, Type)
+        {
+            this.Name = Name;
+        }
+
+        public override string GetName()
+        {
+            return Name.GetName();
+        }
+
+        public override void PrintLeft(TextWriter Writer)
+        {
+            Child.Print(Writer);
+            Writer.Write("::");
+            Name.Print(Writer);
+        }
+    }
+}