device-manager: Add a new module to keep track of the names and descriptions of various sinks.
This will be used as the basis for a queryable system for past and present devices, initially for use in KDE.
Currently all this module does is save lists of sinks/sources and their descriptions, so it needs to
gain a protocol extension to make this queryable.
As things stand it will save the device descriptions of all sinks and restore them if they differ from whats on record.