rust: Add some unit tests for parse_byte_size in config Differential Revision: https://phab.mercurial-scm.org/D10022

rust: Move config value parsing functions to a new module Differential Revision: https://phab.mercurial-scm.org/D10021

rhg: Add support for the blackbox extension Only `command` and `commandfinish` events are logged. The `dirty`, `logsource`, `track` and `ignore` configuration items are not supported yet. To indicate commands executed without Python, a `(rust) ` prefix is added in corresponding log messages. Differential Revision: https://phab.mercurial-scm.org/D10012

blackbox: Remove misleading quotes in config example This example previously looked like quotes were part of configuration file syntax, and the parsed `date-format` value was the part inside of them. This is not the case: config syntax only parses quotes in list values. Instead using that config would result in literal quotes being written to `.hg/blackbox.log` as part of the date format. This changes the example to what was probably intended. Differential Revision: https://phab.mercurial-scm.org/D10011

rust: Add a log file rotation utility This is ported to Rust from `mercurial/loggingutil.py`. The "builder" pattern is used to make it visible at call sites what the two numeric parameters mean. In Python they might simply by keyword arguments. Differential Revision: https://phab.mercurial-scm.org/D10010

rust: Add a `ConfigValueParseError` variant to common errors Configuration files are parsed into sections of key/value pairs when they are read, but at that point values are still arbitrary bytes. Only when a value is accessed by various parts of the code do we know its expected type and syntax, so values are parsed at that point. Let’s make a new error type for this latter kind of parsing error, and add a variant to the common `HgError` so that most code can propagate it without much boilerplate. Differential Revision: https://phab.mercurial-scm.org/D10009

rust: Add config parsing support for more value types * Rust `str` (ASCII or UTF-8) * Integer * Byte quantities Differential Revision: https://phab.mercurial-scm.org/D10008