[csharp-netcore] Add support for ComVisible, CLSCompliant attributes

[wing328]

• add support for ComVisible x-com-visible, CLSCompliant x-cls-compliant attributes
• fix incorrect anyOf mustache tag

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cc @mandrean (2017/08) @frankyjuang (2019/09) @shibayan (2020/02) @Blackclaws (2021/03) @lucamazzanti (2021/05)