[Bug] Named ValueTuple returns is not distinguished

[filzrev]

Describe the bug

When generating API metadata for named ValueTuple with same type but different argument names.
Generated API document don't distinguish these ValueTuples.

To Reproduce

1. Run docfx metadata command to following code

public class ValueTupleTests
{
    public static (int Ret1, int Ret2) Method1() => (0, 0);
    public static (int Ret3, int Ret4) Method2() => (0, 0);
    public static (int, int) Method3() => (0, 0);
}

2.1. When running on Debug mode with Visual Studio. Debug.Assert failed at following lines.

• ReferenceItem.cs#L138
• ReferenceItem.cs#L144

2.2. When running on Release mode.
Generated HTML display following Returns contents for ALL 3-methods

Returns
(int Ret1, int Ret2)

Expected behavior
Named ValueTuple returns contents are correctly displayed.

Context (please complete the following information):

• OS: Windows
• Docfx version: [e.g.2.75.3]

[filzrev]

Close this issue as dup of #9775 #8695