Use the Filter Bar component for scoping Issue Boards

Problem to solve

The Issue Board "Scope" controls are way behind the capabilities of the filter bar. We are essentially maintaining two different controls for scoping a board when we could just use one.

Proposal

• Use the filter bar component to set the global scope for the board
• Global scope becomes just one of many possible saved filters within a Board view.

Context

This is a follow on from the initial MVC for adding iterations - #35290 (closed)