Add support for EventInstantAware notifications

Add support for EventInstantAware notifications

This patch adds support for transmitting DOMEvent contents to
Binding Notifications through the EventInstantAware interface.

The design is such that binding-dom-adapter recognizes DOMEvent
and extracts the instant from it and uses the appropriate codec
call to instantiate a proxy Notification.

On codec side of things, the NotificationCodecContext maintains
a distinct Proxy, which also implements EventInstantAware and
when asked to create a proxy with an instant uses that instead
of the usual LazyDataObject to handle it. In order to make things
seamless and to not impact other LazyDataObject users, this
alternative proxy is serviced by an intermediate InvocationHandler,
which checks if the call is to eventInstance() and if not, it will
delegate to the normal LazyDataObject instance.

JIRA: MDSAL-282
Change-Id: I0dda9a55e4da6231c9bd3be03121a236ce187e47
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>