Implement SDP buffer management

As a Telescope Operator trying to run many observations in sequence, I want to be sure that full-resolution visibilities are reliably evacuated from the buffer, while valuable data products are kept / migrated to stores managed by data lifecycle management.

1. Implement data product data flows and associated reservations in the configuration database
   1. Processing scripts should create them and claim reservations immediately
   2. Buffer manager should also create them for "orphaned" data products in the buffer (to represent in the configuration database that these objects are about to be deleted!)
2. Data lifecycle management should reserve data products that it wants to deliver - might require implementing a data lifecycle management interface service
   1. (Might want to move data product registration model to also be data-flow-based)
   2. Stretch: Implement request to data lifecycle management service to copy/move-in data products
3. Implement either as part of an SDP buffer manager or platform interface ("Helm deployer") deleting objects without reservations
   1. For a first version we might especially implement it as a move into a "recycle bin" area instead of an actual "delete" - to make sure we don't lose data
   2. Might want to implement some slack (~10 minutes?) to make sure we give other services a chance to add reservations
   3. Could especially disable this entirely if - e.g. - the data lifecycle management interface is not currently active