[a11y] Handle tooltip/tap/longPress semantics events

[swift-kim]

I just saw some SemanticsEvent messages not handled by our AccessibilityChannel in the console output when hovering/clicking button widgets with a mouse.

[I] accessibility_channel.cc: operator()(33) > Received tooltip message.
[I] accessibility_channel.cc: operator()(33) > Received tap message.

Should we address these? Actually the mouse pointer is disabled when the Screen Reader is enabled (on TV), so I'm not sure we need to address any of these.