Add option to block incoming requests from being accepted

[DerAndereAndi]

Right now every incoming connection request is handled and it can go through and trigger a pairing attempt. If the pairing is denied, it should be possible to disallow even a connection attempt right away from the remote service.

It might be useful to block it for some time only. Because if both block the attempt completely, the devices might not be able to be paired again if required later on.