Assemble/force: make it possible to "force" a new device in a reshape.

Assemble/force: make it possible to "force" a new device in a reshape.

Normally we do not "force"-assemble devices which are in the
middle of recovery, as they are unlikely to have useful data.

However, when a reshape increases the number of devices,
the newly added devices appear to be recovering because they
do not have complete data on them yet, but then they aren't expected
to until the reshape completes.
So in this case, it can be appropriate to force-assemble them.

Reported-by: "Jonathan Harker (Jesusaurus)" <jesusaurus@gentlydownthe.net>
Signed-off-by: NeilBrown <neilb@suse.de>