"coredumpctl info" behavior had been changed since systemd-v232, we need to
support both version.
Before systemd-v232, it was simple.
It print 'Coredump' field only when the coredump exists on filesystem.
Otherwise print nothing.
After the change made on systemd-v232, it become more complex.
It always print 'Storage' field even the coredump does not exists.
Not just available/unavailable, it describe more:
- Storage: none
- Storage: journal
- Storage: /path/to/file (inacessible)
- Storage: /path/to/file
To support both of them, we need to detect message version first, then
try to detect coredump path.
Fixes: #6789
reference: 47f5064207
967084b567