Refactor NotificationMenuRowPlugin to not require the GutsContent to be a View

For legacy reasons the design of the interface forced us to require
a dummy view instead of being able to provide a ComposeView directly
and keep it separate from the GutsContent interface.

This change should be no-op everywhere. I separated out this refactor
to mitigate the risk of introducing BundleHeaderGuts UI together with
this change.

Bug: 409748420
Test: REFACTOR_ONLY
Flag: EXEMPT refactor
Change-Id: I0ae0b921938022d6ed5dc71b4936aaf4ac070dac