Similar to what qtdemux does in `gst_qtdemux_stream_update_segment()`,
in which case we want to resend tags according to our position.
By setting the changed flag for all stream tags we ensure they will all
be (re-)send as we progrees.
This notably ensures that rotation tags are not lost when video players
finish playback and jump back to the beginning of a video.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/8429>
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