[RFE]Give the detailed information to users for locked node

[Tao Li]

In many scenarios，ironic-conductor will lock the bare metal node to avoid operation race. Otherwise，it only records the name of host which hosts the ironic-conductor. Users don't konw which operation locks the bare metal node. So we should record the reason to db and tell users in some way such as raise an exception with the reason.
I think we should use a blueprint to implement it.

[Kaifeng Wang (kaifeng)]

It's a straightforward solution I think expanding some context would reduce the need for a spec?
Records the reason of and exclusive lock to to the driver_internal_info, and when a request fails to lock the node, include the reason in the exception.
It seems nobody is working on this, taking assignment.