We probably want to introduce multiple explain subcommands and
overloading `explain` to explain it all seems like a bad idea.
We may want to introduce a subcommand to explain config options and
config options may end up having the same name as their rules, e.g. the
current `banned-api` is both a rule name (although not yet exposed to
the user) and a config option.
The idea is:
* `ruff rule` lists all rules supported by ruff
* `ruff rule <code>` explains a specific rule
* `ruff linter` lists all linters supported by ruff
* `ruff linter <name>` lists all rules/options supported by a specific linter
(After this commit only the 2nd case is implemented.)
This commit greatly simplifies the implementation of the CLI,
as well as the user expierence (since --help no longer lists all
options even though many of them are in fact incompatible).
To preserve backwards-compatability as much as possible aliases have
been added for the new subcommands, so for example the following two
commands are equivalent:
ruff explain E402 --format json
ruff --explain E402 --format json
However for this to work the legacy-format double-dash command has to
come first, i.e. the following no longer works:
ruff --format json --explain E402
Since ruff previously had an implicitly default subcommand,
this is preserved for backwards compatibility, i.e. the following two
commands are equivalent:
ruff .
ruff check .
Previously ruff didn't complain about several argument combinations that
should have never been allowed, e.g:
ruff --explain RUF001 --line-length 33
previously worked but now rightfully fails since the explain command
doesn't support a `--line-length` option.
`ruff --help` previously listed 37 options in no particular order
(with niche options like --isolated being listed before before essential
options such as --select). This commit remedies that and additionally
groups the options by making use of the Clap help_heading feature.
Note that while the source code has previously also referred to
--add-noqa, --show-settings, and --show-files as "subcommands"
this commit intentionally does not list them under the new
Subcommands section since contrary to --explain and --clean
combining them with most of the other options makes sense.
