Add 'zpool status -e' flag to see unhealthy vdevs

When very large pools are present, it can be laborious to find
reasons for why a pool is degraded and/or where an unhealthy vdev
is. This option filters out vdevs that are ONLINE and with no errors
to make it easier to see where the issues are. Root and parents of
unhealthy vdevs will always be printed.

Testing:
ZFS errors and drive failures for multiple vdevs were simulated with
zinject.

Sample vdev listings with '-e' option

• All vdevs healthy NAME STATE READ WRITE CKSUM iron5 ONLINE 0 0 0

• ZFS errors NAME STATE READ WRITE CKSUM iron5 ONLINE 0 0 0 raidz2-5 ONLINE 1 0 0 L23 ONLINE 1 0 0 L24 ONLINE 1 0 0 L37 ONLINE 1 0 0

• Vdev faulted NAME STATE READ WRITE CKSUM iron5 DEGRADED 0 0 0 raidz2-6 DEGRADED 0 0 0 L67 FAULTED 0 0 0 too many errors

• Vdev faults and data errors NAME STATE READ WRITE CKSUM iron5 DEGRADED 0 0 0 raidz2-1 DEGRADED 0 0 0 L2 FAULTED 0 0 0 too many errors raidz2-5 ONLINE 1 0 0 L23 ONLINE 1 0 0 L24 ONLINE 1 0 0 L37 ONLINE 1 0 0 raidz2-6 DEGRADED 0 0 0 L67 FAULTED 0 0 0 too many errors

• Vdev missing NAME STATE READ WRITE CKSUM iron5 DEGRADED 0 0 0 raidz2-6 DEGRADED 0 0 0 L67 UNAVAIL 3 1 0

• Slow devices when -s provided with -e NAME STATE READ WRITE CKSUM SLOW iron5 DEGRADED 0 0 0 - raidz2-5 DEGRADED 0 0 0 - L10 FAULTED 0 0 0 0 external device fault L51 ONLINE 0 0 0 14

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Cameron Harr <harr1@llnl.gov>
Closes #15769