rhg: Switch rhg.ignored-extensions config to Python-compatible list syntax This includes the ability to have an extension name/path that contains a comma, by double-quoting it. Differential Revision: https://phab.mercurial-scm.org/D11390

rhg: Port Python’s `ui.configlist` as `Config::get_list` This new method is not used yet outside of its own unit tests, so this changeset should make no observable change. The Rust parser implementation attempts to exactly replicate the behavior of the Python one, even in edge cases where that behavior is… surprising. New unit tests capture some of these edge cases. This started as a line-by-line port. The main changes are: * Pass around a parser mode enum instead of parser functions * Inline the whole parser into one function * Use `[u8]::get` which returns an `Option`, instead of indexing after explicitly checking the length. Differential Revision: https://phab.mercurial-scm.org/D11389

rust: Generalize the `trim_end_newlines` utility of byte strings … into `trim_end_matches` that takes a callack. Also add `trim_start_matches`. Differential Revision: https://phab.mercurial-scm.org/D11388

dirstate-item: move the C implementation to the same logic Now that we know were we are going, we can update the C implementation. Differential Revision: https://phab.mercurial-scm.org/D11387

dirstate-item: introduce low level C function Since a lot of logic is about to change, we need to isolate it into bits that are easy reusable in the rest of the C code. Especially we need to split the part that do the pure logic from the part that do the Python wrapping. Differential Revision: https://phab.mercurial-scm.org/D11386

dirstate-item: factor some code in the C implementation We have both `dirstate_item_from_v1_meth`, a class method, and `dirstate_item_from_v1_data`, a function taking low level C argument. Lets implement the former with the later. Differential Revision: https://phab.mercurial-scm.org/D11385

dirstate-item: `dirstate_item_from_v1_data` replaces make_dirstate_item For different format, we will need multiple capsule anyways. Differential Revision: https://phab.mercurial-scm.org/D11384