Investigate peermissioned launch of Observer Node

[hawk248]

So that we have a control on how many ON's are being created and adding load on the MainNet.

[ashcherbakov]

Any validator node can control what (and hence how many) observer nodes are connected to the given validator nodes by configuring firewall rules in such a way, that only given Observer nodes (domains or IPs) are whitelisted. A connection from an unknown Observer node will be rejected on the firewall level.

More detailed recommendations and more experiments will be done in the scope of #100.