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/ParentNode.cs

@@ -0,0 +1,17 @@
+namespace Ryujinx.HLE.HOS.Diagnostics.Demangler.Ast
+{
+    public abstract class ParentNode : BaseNode
+    {
+        public BaseNode Child { get; private set; }
+
+        public ParentNode(NodeType Type, BaseNode Child) : base(Type)
+        {
+            this.Child = Child;
+        }
+
+        public override string GetName()
+        {
+            return Child.GetName();
+        }
+    }
+}