Move missing accessibility API declarations to OakAppKit.h
Add OakSetAccessibilityLabel function

This function makes it easy to set accessibility "labels" for UI elements.
It is flexible - takes care of NSView vs. NSControl case, labels can be
specified directly as a string or as a user interface element.
Add ability to specify AX labels in UI functions

Accessibility labels now can be specified conveniently as a parameter
of a UI construction function.
Add accessibility labels to Find dialog
Use UI creation functions for accessibility in status bar
Add my work email as contributor address
Post find feedback accessibility announcements
Notify VoiceOver user of find window status bar changes

We don’t have a specific element associated with the result being announced so we use the current responder (unless it has accessibility ignored, in which case we do not post any notification).

Using the current responder is not ideal, but I do not know how we can either associate the notification with the find panel or post it as a global notification.