Add results summary to header of all default issue queue views

Problem/Motivation

It's really helpful for folks using an issue queue to see how many results match any given set of filters.

Proposed resolution

Since the default views are already using a full pager, let's add the default 'Global: Result summary' header to all of our default views.

Remaining tasks

1. Do it.
2. Reviews.
3. RTBC.
4. Commit.

User interface changes

Views result summaries would appear at the top of all issue queue listings.

API changes

N/A

Data model changes

N/A

Release notes snippet

TBD.