Add some missing aural button labels for accessibility

Summary:
Ref T13164. See PHI823. (See that issue for some more details and discussion.)

Add aural labels to various buttons which were missing reasonable aural labels.

The "Search" button (magnifying glass in the global search input) had an entire menu thing inside it. I moved that one level up and it doesn't look like it broke anything (?). All the other changes are pretty straightforward.

Test Plan:

• Will follow up on the issue to make sure things are in better shape for the reporting user.

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13164

Differential Revision: https://secure.phabricator.com/D19594