Avoid allocations in .Parse methods (#3760)

* Avoid allocations in .Parse methods

Use the Span overloads of the Parse methods when possible to avoid string allocations and remove one unnecessarry array allocation

* Avoid another string allocation

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

@@ -918,7 +918,7 @@ namespace Ryujinx.HLE.HOS.Diagnostics.Demangler
                 return -1;
             }
 
-            return int.Parse(part.Substring(0, numberLength));
+            return int.Parse(part.AsSpan(0, numberLength));
         }
 
         private string ParseNumber(bool isSigned = false)