unneeded_synthesized_initializer rule does not detect violations in a struct nested inside a class

[mildm8nnered]

New Issue Checklist

• Updated SwiftLint to the latest version
• I searched for existing GitHub issues

Describe the bug

A clear and concise description of what the bug is.

Given

class Foo {
    struct Bar {
        let baz: Int

        init(baz: Int) {
            self.baz = baz
        }
    }
}

unneeded_synthesized_initializer will fail to detect the violation here.

Environment

• SwiftLint version (run swiftlint version to be sure)? 0.52.4

• Installation method used (Homebrew, CocoaPods, building from source, etc)? CocoaPods

• Which Xcode version are you using (check xcodebuild -version)?

14.2

• Do you have a sample that shows the issue? Run echo "[string here]" | swiftlint lint --no-cache --use-stdin --enable-all-rules
  to quickly test if your example is really demonstrating the issue. If your example is more
  complex, you can use swiftlint lint --path [file here] --no-cache --enable-all-rules.

See above