Add chutney support for FallbackDirs
Just like chutney adds DirAuthority lines, it should add a FallbackDir line for each relay / exit. This will allow us to test #15775 (moved) / #4483 (moved).
Just like chutney adds DirAuthority lines, it should add a FallbackDir line for each relay / exit. This will allow us to test #15775 (moved) / #4483 (moved).