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/SpecialSubstitution.cs

@@ -0,0 +1,89 @@
+using System.IO;
+
+namespace Ryujinx.HLE.HOS.Diagnostics.Demangler.Ast
+{
+    public class SpecialSubstitution : BaseNode
+    {
+        public enum SpecialType
+        {
+            Allocator,
+            BasicString,
+            String,
+            IStream,
+            OStream,
+            IOStream,
+        }
+
+        private SpecialType SpecialSubstitutionKey;
+
+        public SpecialSubstitution(SpecialType SpecialSubstitutionKey) : base(NodeType.SpecialSubstitution)
+        {
+            this.SpecialSubstitutionKey = SpecialSubstitutionKey;
+        }
+
+        public void SetExtended()
+        {
+            Type = NodeType.ExpandedSpecialSubstitution;
+        }
+
+        public override string GetName()
+        {
+            switch (SpecialSubstitutionKey)
+            {
+                case SpecialType.Allocator:
+                    return "allocator";
+                case SpecialType.BasicString:
+                    return "basic_string";
+                case SpecialType.String:
+                    if (Type == NodeType.ExpandedSpecialSubstitution)
+                    {
+                        return "basic_string";
+                    }
+
+                    return "string";
+                case SpecialType.IStream:
+                    return "istream";
+                case SpecialType.OStream:
+                    return "ostream";
+                case SpecialType.IOStream:
+                    return "iostream";
+            }
+
+            return null;
+        }
+
+        private string GetExtendedName()
+        {
+            switch (SpecialSubstitutionKey)
+            {
+                case SpecialType.Allocator:
+                    return "std::allocator";
+                case SpecialType.BasicString:
+                    return "std::basic_string";
+                case SpecialType.String:
+                    return "std::basic_string<char, std::char_traits<char>, std::allocator<char> >";
+                case SpecialType.IStream:
+                    return "std::basic_istream<char, std::char_traits<char> >";
+                case SpecialType.OStream:
+                    return "std::basic_ostream<char, std::char_traits<char> >";
+                case SpecialType.IOStream:
+                    return "std::basic_iostream<char, std::char_traits<char> >";
+            }
+
+            return null;
+        }
+
+        public override void PrintLeft(TextWriter Writer)
+        {
+            if (Type == NodeType.ExpandedSpecialSubstitution)
+            {
+                Writer.Write(GetExtendedName());
+            }
+            else
+            {
+                Writer.Write("std::");
+                Writer.Write(GetName());
+            }
+        }
+    }
+}