Advantages of having typical errors at a common place:
* Error message styling can be harmonized
* Existing messages can be reused
* Overview of prefixes ('error: ', 'warning: ')
* Manage how to print them to the console
To support this, we first must use an async entrypoint to the CLI, which
we do by changing the lint and analyze commands to conform to
`AsyncParsableCommand`.
The in order to map over the closures with suspension points, we pull in
CollectionConcurrencyKit as a new dependency.
This change does not touch SwiftLintFramework, only the CLI target.
There is no real benefit for this option. Files and folders to lint/analyze
can be passed to `swiftlint` as last arguments. There cannot be multiple
`--path` arguments. If there is more than one only the last path is considered.
Danny Mösch
