Adds --working-directory command line option

[mildm8nnered]

Adds a --working-directory argument to lint and analyze, for users who cannot easily control the current directory when executing SwiftLint (e.g. in some plugin and CI scenarios).

Addresses #5424

This is required because .swiftlint.yml's in the current directory are treated slightly differently to .swiftlint.yml's found deeper in the tree.

For example:

$ pwd
/Users/some.user/Documents/Source/SwiftLint
$
$ swiftlint --quiet --reporter summary
Linting Swift files in current working directory
+-----------------+--------+-------------+--------+----------+--------+------------------+-----------------+
| rule identifier | opt-in | correctable | custom | warnings | errors | total violations | number of files |
+-----------------+--------+-------------+--------+----------+--------+------------------+-----------------+
| Total           |        |             |        |        0 |      0 |                0 |               0 |
+-----------------+--------+-------------+--------+----------+--------+------------------+-----------------+
$
$
$ cd ../..
$ pwd
/Users/some.user/Documents
$
$
$ swiftlint  --quiet --reporter summary Source/SwiftLint
Linting Swift files at paths Source/SwiftLint
+---------------------+--------+-------------+--------+----------+--------+------------------+-----------------+
| rule identifier     | opt-in | correctable | custom | warnings | errors | total violations | number of files |
+---------------------+--------+-------------+--------+----------+--------+------------------+-----------------+
| file_name           | yes    | no          | no     |       18 |      0 |               18 |              18 |
| type_name           | no     | no          | no     |        8 |      0 |                8 |               8 |
| file_header         | yes    | no          | no     |        5 |      0 |                5 |               5 |
| trailing_comma      | no     | yes         | no     |        4 |      0 |                4 |               1 |
| empty_xctest_method | yes    | no          | no     |        1 |      0 |                1 |               1 |
| legacy_objc_type    | yes    | no          | no     |        1 |      0 |                1 |               1 |
| let_var_whitespace  | yes    | no          | no     |        1 |      0 |                1 |               1 |
+---------------------+--------+-------------+--------+----------+--------+------------------+-----------------+
| Total               |        |             |        |       38 |      0 |               38 |              21 |
+---------------------+--------+-------------+--------+----------+--------+------------------+-----------------+
Done linting! Found 38 violations, 0 serious in 646 files.
$
$
$ swiftlint --quiet --reporter summary --working-directory Source/SwiftLint 
Linting Swift files in current working directory
+-----------------+--------+-------------+--------+----------+--------+------------------+-----------------+
| rule identifier | opt-in | correctable | custom | warnings | errors | total violations | number of files |
+-----------------+--------+-------------+--------+----------+--------+------------------+-----------------+
| Total           |        |             |        |        0 |      0 |                0 |               0 |
+-----------------+--------+-------------+--------+----------+--------+------------------+-----------------+

We could assume that the first .swiftlint.yml we encountered was the "main" one, but this would not be true in the unusual, but valid case, where users intentionally did not have a "main" .swiftlint.yml. Additionally, some SwiftLint code, specifically some reporters, assume that the current directory is also the top-level directory of the project.

All relative paths on the command line and in configuration files will be treated as relative to the specified working directory.

[SwiftLintBot]

	17 Messages
📖	Linting Aerial with this PR took 1.02s vs 0.98s on main (4% slower)
📖	Linting Alamofire with this PR took 1.37s vs 1.36s on main (0% slower)
📖	Linting Brave with this PR took 8.04s vs 8.03s on main (0% slower)
📖	Linting DuckDuckGo with this PR took 4.39s vs 4.42s on main (0% faster)
📖	Linting Firefox with this PR took 11.35s vs 11.34s on main (0% slower)
📖	Linting Kickstarter with this PR took 10.07s vs 10.06s on main (0% slower)
📖	Linting Moya with this PR took 0.56s vs 0.56s on main (0% slower)
📖	Linting NetNewsWire with this PR took 2.77s vs 2.75s on main (0% slower)
📖	Linting Nimble with this PR took 0.82s vs 0.81s on main (1% slower)
📖	Linting PocketCasts with this PR took 8.68s vs 8.68s on main (0% slower)
📖	Linting Quick with this PR took 0.45s vs 0.46s on main (2% faster)
📖	Linting Realm with this PR took 5.02s vs 5.05s on main (0% faster)
📖	Linting Sourcery with this PR took 2.53s vs 2.51s on main (0% slower)
📖	Linting Swift with this PR took 4.93s vs 4.92s 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 19.22s vs 19.25s on main (0% faster)
📖	Linting WordPress with this PR took 14.21s vs 14.22s on main (0% faster)

Generated by 🚫 Danger

[mildm8nnered]

So originally this throw produced the following eventual output:

Error: couldNotChangeToWorkingDirectory(path: "Source/SwiftLintt")

because the thrown error eventually gets passed to MessageInfo(error: Error, type: ParsableArguments.Type) from the swift-argument-parser. Ideally it would get caught there by

      case let error as LocalizedError where error.errorDescription != nil:
        self = .other(message: error.errorDescription!, exitCode: .failure)

but it was not, because Issue's implementation of errorDescription (var errorDescription: String) does not match the LocalizedError protocol requirement (var errorDescription: String?).

I've fixed that, but because of the way the thrown error is now printed, we get

Error: warning: Could not change working directory to 'Source/SwiftLintt'.

One way around that would just be to brute-force:

if !FileManager.default.changeCurrentDirectoryPath(workingDirectory) {
    Issue.couldNotChangeToWorkingDirectory(path: workingDirectory).print()
    exit(2)
}

Another possibility would be to remove our warning: and error: prefixes from errorDescription, but to add them back in Issue.print() - most usages look like that would be ok, but I'm not sure how confident I am that all of them would be.

[mildm8nnered]

Switched to SwiftLintError.usageError, which produces: `Error: Could not change working directory to 'Source/SwiftLintt'

I would kind of expected. throwing an Issue to work though.

[mildm8nnered]

Not sure what a good default is here