If idx is one past the last peer, the behavior is the same as
append_peer.
Otherwise, the peer will be at idx and replace the peer instance at that index. Note that if a peer with the same
public-key exists on another index, then that peer will also be replaced. In that case, the number of peers will shrink by one (because
the one at idx got replace and then one with the same public-key got removed). This also means, that the resulting index
afterwards may be one less than idx (if another peer with a lower index was dropped).
| this |
the SettingWireGuard instance |
| peer |
the WireGuardPeer instance to set. This seals |
| idx |
the index, in the range of 0 to the number of peers (including). That means, if |