fix: strengthen Weston runtime discovery and recovery helpers

Improve Weston runtime helper logic in lib_display.sh for dynamic
Wayland runtime discovery and stricter runtime health validation.

Changes include:
- add richer Weston runtime snapshots with service, socket, process,
  runtime user, uid, and runtime directory details
- gate runtime health on systemd weston.service and weston.socket
  state instead of relying only on socket presence
- support optional cleanup and relaunch flow for failed Weston runtime
- stop stale weston.service and weston.socket and reset failed
  systemd state before relaunch
- log runtime context before and after relaunch attempts
- prefer discovered Weston service user runtime directory such as
  /run/user/<uid> when available
- avoid client probing from runtime helpers so preflight remains a
  pure runtime check

Signed-off-by: Srikanth Muppandam <smuppand@qti.qualcomm.com>

Author: smuppand