Huawei dwdm

[yatimqsh]

Support Huawei OptiXtrans which are series of DWDM devices

To support Huawei OptiXtrans DC908 Series we add a new device type because config structure is to different from usual huawei. Therefore separate .rul and separate run_... methods on generators are prefered.

We keep it in hw.Huawei hierarchy but it will not be handled by run_huawei generator akin to what we do with hw.Cisco.Nexus

[azryve]

Please also write a more involved description, this is not a trivial commit at least we need to explain that

• it is a product line of huawei dwdm devices which currently have only one model DC908
• we adding it because we expect device to have a different config structure with block that are missing from usual huawei struff
• we keep it in hw.Huawei hierarchy but it will not be handled by run_huawei generator akin to what we do with hw.Cisco.Nexus