In some cases the position is supplied from a "live" source
that keeps changing its value at repeated calls. This typically
happens when forwarding to another backend with unpredictable
position values. The problem is that as soon as the backend
system has a position discontinuity, any previously created
PositionSupplier now returns a position that no longer makes
sense in the context of the State object it belongs to.
ForwardingSimpleBasePlayer already works around this issue by
having a util class to disconnect these live sources. This
change moves the same util to SimpleBasePlayer itself so it
can be reused by other implementations.
PiperOrigin-RevId: 713658046
9608ae4e3d