First: the buffer is pushed on the encoding filesink only *after* the
checkpoints, leading to wrong ordering in expectations.
The second one is about EOS being posted on the bus *before* the
stop action is executed, leading to the action never being executed.
That action was plain useless as the default behavior of validate
scenario is to internally create a "stop" action on EOS (unless
disabled by user).
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/-/merge_requests/968>
Add a way for applications to specify that the underlying file is
growing which implies that the source won't EOS when reaching the end
of the file but instead start monitoring it and start reading it again
whenever a change is detected.
Also add a validate test to check the behavior
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/-/merge_requests/937>
