ui/cocoa: Add console items to the View menu

ui/cocoa: Add console items to the View menu

Add any console that is available to the current emulator as a
menu item under the View menu.

Signed-off-by: John Arbuckle <programmingkidx@gmail.com>
[PMM: Adjusted to apply after zoom-to-fit menu item was added;
 create the View menu at the same time as all the others, and only
 add the dynamically-determined items to it later]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>