manifest: remove _repo from manifestctx objects We were storing the repo on the manifestctx objects so that they could access the manifestlog via repo.manifestlog, which would refresh the structure if it became out of date. This caused probems however when we want to have multiple manifest logs in memory at once, like when transitioning to tree manifest from flat manifests, since a tree manifest would try to access sub-trees via repo.manifestlog[node], which was the flat manifest. The solution is to just not store the repo, and instead store the manifestlog that created this context. This removes the invalidation when the in memory manifestlog becomes out of date, but people should probably not be keeping ctx's around that long anyway.

phases: remove experimental.nativephaseskillswitch The native code has been used for a long time. Therefore drop the experimental config option.

manifest: allow specifying the revlog filename Previously we had hardcoded the manifest filename to be 00manifest.i. In our external treemanifest extension, we want to allow writing a treemanifest side by side with a flat manifest, so we need to be able to store the root revisions at a different location (in our extension we use 00manifesttree.i). This patches moves the revlog name to a parameter so we can adjust it.