Add a field for default pipelines in a Stack CR instance

[kaczyns]

This is a child issue of #647.
There is a desire to have a default set of pipelines for a Stack CR. These would be applied to all versions of the stack defined in the CR. A new set of pipeline information (field called pipelines) should be created at the top level of the Stack CR spec section.

The stack controller should use these default stack pipelines if the specific stack version does not contain any. Considered holistically with #762, we now have three places we could be pulling pipelines from when the stack controller is running in Odo mode. Here is the list, in priority order from highest priority to lowest:

1. From the spec.versions[x].pipelines in the Stack CR instance
2. From spec.pipelines in the Stack CR instance
3. From the Kabanero CR instance

Note that when the stack controller is running in Appsody mode, there is no need to use the spec.pipelines in the Stack CR instance, as the kabanero controller is not going to set that field when processing an appsody stack hub. However if it makes the implementation easier, the stack controller could use 1) or 2) in both modes. It should not use 3) in Appsody mode.