unneeded_parentheses_in_closure_argument doesn't work with capture lists

[marcelofabri]

New Issue Checklist

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

Bug Report

Complete output when running SwiftLint, including the stack trace and command used

$ swiftlint lint

Environment

• SwiftLint version (run swiftlint version to be sure)? 0.22.0
• Installation method used (Homebrew, CocoaPods, building from source, etc)? CocoaPods
• Paste your configuration file:

opt_in_rules:
  - unneeded_parentheses_in_closure_argument

• Are you using nested configurations?
  If so, paste their relative paths and respective contents. Nop
• Which Xcode version are you using (check xcode-select -p)? Xcode 9
• 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.

// This should trigger unneeded_parentheses_in_closure_argument
foo.bar { [weak self] (x,y) in }