Add a constrained + aligned wrapper

A frequent need is to constrain a view to its parent with lower priority, and then align it with a required priority. Like an Avatar that I would prefer be bound to the parents edges, but if that's not possible will still maintain a specific alignment, either centered or top aligned.

Requirements:
- Optional priority parameter for the direct constraint
- Optional alignment for the fallback constraint (defaults to center I think?)

No file or test is named; start by locating the existing view-constraint wrapper and its call sites in KitUI. Confirm how direct constraint priority and fallback alignment are represented, then verify that both parameters are optional, with the fallback alignment defaulting to center.

Written by the indexing model from the issue text.