Display stack owner when formatting stacks

Stacks are launched by users but scoped to tenants, so users in the same
tenant currently have no way to know owns each stack.  The same is
especially true to unscoped stack lists.  Since humans are much better
with names than they are with numbers, this adds the stack owner
username to the data returned with each stack.

Co-Authored-By: Anderson Mesquita <andersonvom@gmail.com>
Implements: blueprint stack-display-fields
Change-Id: Ia1386531025096e0eeaf9e98b478c4453fc8cb01
Merge "Display stack owner when formatting stacks"