ui/cocoa: Split [-QemuCocoaView handleEventLocked:]

ui/cocoa: Split [-QemuCocoaView handleEventLocked:]

Currently [-QemuCocoaView handleEventLocked:] parses the passed event,
stores operations to be done to variables, and perform them according
to the variables. This construct will be cluttered with variables and
hard to read when we need more different operations for different
events.

Split the methods so that we can call appropriate methods depending on
events instead of relying on variables.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Tested-by: Rene Engel <ReneEngel80@emailn.de>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-ID: <20240224-cocoa-v12-1-e89f70bdda71@daynix.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>