Support bundle and SIP trace error codes (mpbx-support)

Raised by /api/v1/system/support-bundle and /api/v1/system/sip-trace/... (W7-OBS-01b). All of them need a system-scope credential. Guide: Support bundle and SIP trace.

Code	Kind	Meaning	What to do
MPBX-SIPTRACE-NOT-FOUND	not_found	The captured call is unknown: it was never captured, it is older than the retention, it was deleted, or the process restarted (the capture store is in memory).	List the captured calls again.