Ossku type
Defines values for Ossku. 
KnownOssku can be used interchangeably with Ossku,
this enum contains the known values that the service supports.
Known values supported by the service
CBLMariner: Use Mariner as the OS for node images. 
Windows2019: Use Windows2019 as the OS for node images. 
Windows2022: Use Windows2022 as the OS for node images.
type Ossku = string