[JsonGen/StubGen] Support fixed arrays

[sebaszm]

struct Fixated {
  struct BluetoothInfo {
    uint8_t Addr[6]; // a bt address
    uint32_t UUIDs[8];
    string Descriptions[8];
  };

  uint8_t IpAddr[4]; // an ip address
  BluetoothInfo BtAddr[5]; 
  uint8_t Edid[128] /* @encode:base64 */;
};

virtual Core::hresult Amazing(Fixated param[4] /* @inout */) = 0;

Supports all types including PODs, supports nesting.