`libp2p@2.x.x` will remove the `localPeer` argument from the
`secureInbound` and `secureOutbound` methods of the
`ConnectionEncrypter` interface.

Unfortunately the `js-libp2p` monorepo has a depdendency on this
module so the change cannot be released until this module is
compatible... with the unreleased change.

This PR tests the first argument to `secureInbound` and
`secureOutbound` to ensure that it is actually a `PeerId`. If
not it shuffles all the arguments along by one place.

This PR can be reverted and the first argument removed once
`libp2p@2.x.x` is released.