auto-upgrade: introduce a way to auto-upgrade to/from tracked-hint This is similar to what we introduced for `share-safe`, but apply to the tracked-hint feature. Differential Revision: https://phab.mercurial-scm.org/D12613

upgrade: split some logic from UpgradeOperation The logic for automatic-upgrade and the upgrade-repo should be able to use the same code. However that code often need an UpgradeOperation object to function. So we start spliting the Operation into a minimal component that we will be able to reuse outside of the "classic" upgrade path. We will put the base-class to use in the next changeset. Differential Revision: https://phab.mercurial-scm.org/D12612

auto-upgrade: introduce a way to auto-upgrade to/from share-safe This is the first "automatic-upgrade" capability. In the following commits, similar features are coming for other "fast to upgrade" formats. This is different from the `safe-mismatch.source-not-safe` and `safe-mismatch.source-safe` configuration that deal with mismatch between a share and its share-source. Here we are dealing with mismatch between a repository configuration and its actual format. We will need further work for cases were the repository cannot be locked. A basic protection is in place to avoid a infinite loop for now, but it will get proper attention in a later changeset. Differential Revision: https://phab.mercurial-scm.org/D12611

rust: make requirements public These can be used by any client crates (including `rhg`), no need to make them private to the crate. Differential Revision: https://phab.mercurial-scm.org/D12610