Once https://github.com/dotnet/runtime/pull/111598 propagates to the tools runtime, we should switch the runtime tools (ILCompiler, crossgen2, etc.) to use it. The task is to: * Delete the src/libraries/Common/src/System/Reflection/Metadata/TypeNameHelpers.cs file * Remove the references to this file from all project files * Replace the uses of `TypeNameHelpers.Unescape` with `TypeName.Unescape` * Replace the uses of `TypeNameHelpers.Split` with the `Namespace` and `Name` properties on the `TypeName` type.