Some seek operations are currently filtered in the base classes if
the target index is not explicitly specified and the implicitly
assumed operation doesn't have an obvious target index. (Example:
calling seekToNext() at the last item in a playlist)
This is too opinionated because the actual player implementation
using this base class may be able to handle this seek request (e.g.
by adding new items on the fly or using other logic to select
the most suitable next item).
This can be solved by forwarding all seek requests to the respective
handler methods even if they are a presumed no-op. Also clarify the
Javadoc that the provided index is just an assumption if it wasn't
provided explicitly in the method call.
PiperOrigin-RevId: 624887116
11257ecacb