The prefix was used to filter the properties when loading and
saving but since the conversion to the core provided functions, this
feature is not longer available.
It's not exactly a problem, we could implement the filtering ourselves
afterwards but there is little point because we just ignore the unknown
items and never write invalid items.
Save settings as jason and use a small json compatible tokenizer to
load settings instead of our own less flexible format.
Save settings with a prefix and filter out entries without prefix
Listen for changes in restore.stream metadata and update properties.
Keep a per node entry of the saved target node and use this when
there is no other target node.
When explicitly moving a stream, save the new target node.
