Store last data received from WindowInfosListener

Store the last data received from WindowInfoListener on the client so it
can easily be retrieved when a new caller registers to listen for
updates. This will help with accessibility since they won't need to
register their listener all the time and instead just get the last data
that was sent, immediately.

From the system server process, the data is constantly being updated
because WindowInfo is sent to InputDispatcher when any geometry in SF
changes. If a different process registers for the WindowInfoListener,
it's possible the initial data will be empty since we won't explicitly
request the latest data immediately.

Bug: 222767081
Test: Accessibility register only when enabled
Change-Id: Ib87edde7a14be8584504d5d8d6c41f20bde5c698