rust-matchers: make `Matcher` trait object-safe Before this patch, it is not possible to create a `Matcher` trait-object (like `Box<dyn Matcher>`), because of the use of a generic parameters in some methods, namely `impl AsRef<HgPath>`. While this makes the interface less flexible for callers in theory, it does not change anything in the current codebase. Until something like [1] is implemented, this is a "tradeoff" that we need to make anyway. [1] https://internals.rust-lang.org/t/pre-rfc-expand-object-safety/12693 Differential Revision: https://phab.mercurial-scm.org/D9071

rust: clippy pass This removes some justified warnings and one hard error that, while technically not a bug, was an ugly oversight on my part. Differential Revision: https://phab.mercurial-scm.org/D9094

updaterepo: add deprecation warning We just moved all in-tree callers off of the function, but we're leaving it here for a bit to help extension writers. Differential Revision: https://phab.mercurial-scm.org/D9110