balanceCount
Since channels are always closed when tests finish, there's no need to track them in node's state.
SyncMap
This commit replaces the usage of `sync.Map` with the new struct `SyncMap` to explicitly express the type info used in the map.
This commit adds a new package `lntemp/node` and inside it a new struct `State` is added to track the internal node state. This enables us using the same running nodes accross tests without wrong uncleaned states.
