Add --only-rule command line option

[mildm8nnered]

Addresses #5659

Adds an --only-rule option to the lint and analyze subcommands (--fix is also supported), which behaves as though that single rule was specified in only_rules: in the configuration file.

This is very similar in spirit to the --enable-all-rules command line option. Configuration file settings will be ignored.

A primary use case for this feature is to be able to autocorrect violations of a single rule at a time.

Previously the alternative was to hack the existing .swiftlint.yml file, or to provide a custom one.

 % swiftlint.debug help lint   
OVERVIEW: Print lint warnings and errors

USAGE: swiftlint lint [<options>] [<paths> ...]

ARGUMENTS:
  <paths>                 List of paths to the files or directories to lint.

OPTIONS:
  --only-rule <only-rule> Run only the specified rule, ignoring `only_rules`, `opt_in_rules` and `disabled_rules`.

% swiftlint help analyze
OVERVIEW: Run analysis rules

USAGE: swiftlint analyze [<options>] [<paths> ...]

ARGUMENTS:
  <paths>                 List of paths to the files or directories to analyze.

OPTIONS:
  --only-rule <only-rule> Run only the specified rule, ignoring `only_rules`, `opt_in_rules` and `disabled_rules`.

[SwiftLintBot]

	17 Messages
📖	Linting Aerial with this PR took 1.04s vs 1.01s on main (2% slower)
📖	Linting Alamofire with this PR took 1.37s vs 1.37s on main (0% slower)
📖	Linting Brave with this PR took 8.12s vs 8.08s on main (0% slower)
📖	Linting DuckDuckGo with this PR took 4.6s vs 4.61s on main (0% faster)
📖	Linting Firefox with this PR took 11.47s vs 11.46s on main (0% slower)
📖	Linting Kickstarter with this PR took 10.12s vs 10.15s on main (0% faster)
📖	Linting Moya with this PR took 0.56s vs 0.56s on main (0% slower)
📖	Linting NetNewsWire with this PR took 2.76s vs 2.76s on main (0% slower)
📖	Linting Nimble with this PR took 0.81s vs 0.81s on main (0% slower)
📖	Linting PocketCasts with this PR took 8.72s vs 8.85s on main (1% faster)
📖	Linting Quick with this PR took 0.45s vs 0.46s on main (2% faster)
📖	Linting Realm with this PR took 5.06s vs 5.06s on main (0% slower)
📖	Linting Sourcery with this PR took 2.52s vs 2.53s on main (0% faster)
📖	Linting Swift with this PR took 4.96s vs 4.96s on main (0% slower)
📖	Linting VLC with this PR took 1.33s vs 1.34s on main (0% faster)
📖	Linting Wire with this PR took 19.5s vs 19.33s on main (0% slower)
📖	Linting WordPress with this PR took 14.65s vs 14.66s on main (0% faster)

Generated by 🚫 Danger

[SimplyDanny]

I really look forward to have this. Every so often I mangle the configuration file instead. 🫣