feat: add swiftlint

[kaanbiryol]

Adds SwiftLint support to rules_lint for Swift sources.

Closes #55

This adds lint_swiftlint_aspect, wires SwiftLint binary fetching through the lint tools extension, and updates the Swift example/docs. The aspect supports explicit config inputs, default empty config behavior, baseline files, nested config selection, fix patches, and SARIF machine-readable reports.

Changes are visible to end-users: yes

• Searched for relevant documentation and updated as needed: yes
• Breaking change (forces users to change their own code or config): no
• Suggested release notes appear below: yes

Add SwiftLint as a supported Swift linter.

Test plan

• New test cases added
• Manual testing:

cd examples/swift

bazel test //test:all

# Expected to fail and report the intentional SwiftLint violation.
aspect lint -- //src:all

# Expected to apply the generated SwiftLint fix to the workspace.
aspect lint --fix -- //src:all

# Expected to pass and generate a patch without changing the workspace.
bazel build --config=lint --output_groups=rules_lint_patch --@aspect_rules_lint//lint:fix //src:all

[CLAassistant]

All committers have signed the CLA.

[aspect-workflows]

Bazel 7 (Test)

6 test targets passed

Targets

//format/test:custom_args_test [k8-fastbuild] 379ms
//format/test:ls-files_test [k8-fastbuild]    765ms
//lint/rust:test_human [k8-fastbuild]         107ms
//lint/rust:test_patch [k8-fastbuild]         164ms
//lint/rust:test_sarif [k8-fastbuild]         218ms
//tools/sarif:sarif_test [k8-fastbuild]       96ms

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Bazel 8 (Test)

All tests were cache hits

6 tests (100.0%) were fully cached saving 1s.

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Bazel 9 (Test)

All tests were cache hits

6 tests (100.0%) were fully cached saving 1s.

[kaanbiryol]

Updated to normalize whitespace and look for an actual result object ("results":[{) instead of the exact substring "results": [.

SwiftLint formats SARIF as "results" : [ and can emit empty reports as:

"results" : [

],