Nested array, interface and more

[cklam2]

• Added nested array support (eg [[[String]]])
• Dropped assigning default values
• Mark fields with default value optional, even when it had a ! (see [typescript] non nullable graphql inputs with default values are not optional as ts types #4273)
• Generate C# interface from gql interface
• If request doesn't have input args, don't include the variable arg in Request
• Solved circular dependency issue
• Typo: =>

[dotansimha]

Amazing work. Thank you so much @cklam2 !