This new tool (`dserverdbg`) runs on the host but connects to
darlingserver and makes unmanaged calls to retrieve debugging
information.
The initial set of subcommands available in this tool are `ps`,
`lsport`, `lspset`, and `lsmsg`:
* `ps` lists processes currently registered with the server and how
many Mach ports they have
* `lsport` lists the ports of a given process (via PID) and their
rights and messages counts (for receive rights)
* `lspset` lists the members of a given portset (via PID and port
name) and provides the same information about each port as `lsport`
* `lsmsg` lists the messages of a given port (via PID and port name),
providing sender PID (if available) and size
This tool may be expanded later to allow e.g. modifying logging settings
while darlingserver is running or perhaps searching through and
filtering the logs.
