dirstate-v2: Add `hg debugupgraderepo` command support This command changes changes the file formats used inside an existing repository to what they would be in a new repository with the current config. For example: hg debugupgraderepo --config format.exp-dirstate-v2=1 --run hg debugupgraderepo --config format.exp-dirstate-v2=0 --run If a repository has a dirstate in v1 format, the first command would upgrade it to dirstate-v2. Conversely, if a repository has a dirstate in v2 format, the second command would downgrade it to v1. (Both may also run some unrelated upgrades.) Since `format.exp-dirstate-v2` is currently disabled by default, not specifying it in `--config` or any configuration file would result in the second command. Differential Revision: https://phab.mercurial-scm.org/D10769