> test: fix constructing CNode with invalid inbound_onion
>
> as CNode ctor should only be passed inbound_onion = true
> when the connection is inbound
> net: assert CNode::m_inbound_onion is inbound in ctor
>
> and drop an unneeded check in CNode::ConnectedThroughNetwork()
> net: add CNode::IsInboundOnion() public getter and unit tests
This is a backport of core#20210