localrepo: use peer interfaces We now have a formal abstract base class for peers. Let's transition the peer classes in localrepo to it. As part of the transition, we reorder methods so they are grouped by interface and match the order they are defined in the interface. We also had to change self.ui from an instance attribute to a property to satisfy the @abstractproperty requirement. As part of this change, we uncover the first "bug" as part of enforcing interfaces: stream_out() wasn't implemented on localpeer! This isn't technically a bug since the repo isn't advertising the stream capability, so clients shouldn't be attempting to call it. But I don't think there's a good reason why this is the case. We implement a dummy method to satisfy the interface requriements. We can make localpeer instances streamable as a future enhancement. # no-check-commit Differential Revision: https://phab.mercurial-scm.org/D335