zed: Allow autoreplace and fault LEDs for removed vdevs

Allow zed to autoreplace vdevs marked as REMOVED. Also update
statechange-led zedlet to toggle fault LEDs for REMOVED vdevs.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tony Hutter <hutter2@llnl.gov>
Closes #15281