fastannotate: rip out specialized support for remotefilelog remotefilelog can choose to collaborate with fastannotate for now if it needs to, and in the future when we make good on our longstanding desire to move remotefilelog-like features in-house we'll make sure things are well-supported via a reasonable interface. Differential Revision: https://phab.mercurial-scm.org/D4201

fastannotate: record some TODO items from indygreg's review Some of these I'll address more or less right away, but some will take a while for us to resolve. Differential Revision: https://phab.mercurial-scm.org/D4200