manifest: remove last uses of repo.manifest Now that all the functionality has been moved to manifestlog/manifestrevlog/etc, we can finally change all the uses of repo.manifest to use the new versions. A future diff will then delete repo.manifest. One additional change in this commit is to change repo.manifestlog to be a @storecache property instead of @property. This is required by some uses of repo.manifest require that it be settable (contrib/perf.py and the static http server). We can't do this in a prior change because we can't use @storecache on this until repo.manifest is no longer used anywhere.