[FEATURE] Report the cause of inactivity of a node in case of activation of a unimplemented feature

[alexeykiselev]

Motivation and Purposes

After activation of a unimplemented feature on blockchain the node won't work because of that, but the cause of this is printed in logs only once at the moment of the activation.
On restart the node just doesn't work without any messages in logs.

Specification
Add message that describes the cause of node's inactivity.

Backwards Compatibility
Not affected.