Commands for managing static IP addresses

Added commands:
azure vm static-ip show <vm-name>
azure vm static-ip set <vm-name> <ip-address>
azure vm static-ip remove <vm-name>
azure network vnet static-ip check <vnet> <ip-address>

Added --static-ip option to:
azure vm create
azure vm docker create

@babumuralidharan it seems that all bugs on this feature have been addressed.
@avranju , please review. This PR is assuming we want to merge into MSOT/dev and not send directly upstream.
Fixed.
I am not 100% sure what the state of things is on localization, but it's my impression that the xPlat tools are currently only available in English, and so we are maintaining these strings only in preparation of future localization work.
If we keep maintaining these as resources, we should probably consider making it mandatory for the string to be present in the .json file. Right now if the resource value is missing, the key itself is returned.