In order to support running from both the repository root and from
within Xcode project, and to keep things generally organized, our
primary .swiftlint.yml configuration file lives under macos/.
This change introduces a root-level .swiftlint.yml which limits the file
scope to macos/ and then includes macos/.swiftlint.yml for the rest of
the directives.
This unlocks a few benefits:
- We no longer need to pass an explicit `macos` path argument in any of
our invocations. SwiftLint will do the right thing when run either
from the repository root or from within the macos/ directory.
- It lets us easily exclude the macos/build/ directory (and re-enable
the 'deployment_target' rule). In the previous setup, this was more
challenging than you'd expect due to SwiftLint's path resolution rules
and required passing even more arguments like `--working-directory`.
The only downside is adding a new file to the repository root, but that
feels like the right trade-off given the benefits and conveniences.