Create a Spinnaker Pipeline Struct

For the spinnaker backend, some operations require Application/Pipeline/Type properties.
Create the struct for the most basic operations like checking if these fields exist.

Start by inspecting the spinnaker backend operations that require Application, Pipeline, and Type properties, along with any existing backend structs. Define the basic struct so those operations can check whether these fields exist; done means the relevant operations can use it for those checks.

Written by the indexing model from the issue text.