Exclude Function Builder from `closure_body_length` rule

New Issue Checklist

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

Describe the bug

Function Builder (since Swift 5.1) is recognized as closure, and often triggers closure_body_length violation.

Function Builder is used in SwiftUI and usually over 20 lines (here is an official sample code), so it should be excluded.

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

$ swiftlint lint

Environment

• SwiftLint version (run swiftlint version to be sure)?
  0.39.1
• Installation method used (Homebrew, CocoaPods, building from source, etc)?
  Mint
• Paste your configuration file:

# insert yaml contents here

• Are you using nested configurations?
  If so, paste their relative paths and respective contents.
• Which Xcode version are you using (check xcodebuild -version)?
• 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 triggers a violation: closure_body_length
NavigationView {
    Form {
        Picker(selection: $viewModel.form.argument1, label: Text("Argument1")) {
            ForEach(ViewForm.Argument1.allCases, id: \.self) {
                Text($0.name)
            }
        }
        DatePicker(selection: $viewModel.form.argument,
                    in: ...Date(),
                    displayedComponents: [.date, .hourAndMinute]) {
                    Text("Date")
        }
        Picker(selection: $viewModel.form.argument2, label: Text("Argument2")) {
            ForEach(ViewForm.Argument2.allCases, id: \.self) {
                Text($0.label)
            }
        }
        Picker(selection: $viewModel.form.argument3, label: Text("Argument3")) {
            ForEach(ViewForm.Argument3.allCases, id: \.self) {
                Text($0.label)
            }
        }
        Picker(selection: $viewModel.form.argument4, label: Text("Argument4")) {
            ForEach(ViewForm.Argument4.allCases, id: \.self) {
                Text($0.label)
            }
        }
        Picker(selection: $viewModel.form.argument5, label: Text("Argument5")) {
            ForEach(ViewForm.Argument5.allCases, id: \.self) {
                Text($0.label)
            }
        }
        Picker(selection: $viewModel.form.argument6, label: Text("Argument6")) {
            ForEach(ViewForm.Argument6.allCases, id: \.self) {
                Text($0.label)
            }
        }
        Picker(selection: $viewModel.form.argument7, label: Text("Argument7")) {
            ForEach(ViewForm.Argument7.allCases, id: \.self) {
                Text($0.label)
            }
        }
        Toggle(isOn: $viewModel.form.argument8) {
            Text("Argument8")
        }
    }.navigationBarTitle("Title", displayMode: .inline)
        .navigationBarItems(
            trailing: Button(action: { self.submit() },
                                label: { Text("Submit") }))
}

Start with the closure_body_length rule and reproduce the reported violation using the SwiftUI sample with swiftlint lint --no-cache --enable-all-rules. Trace how Function Builder closures are identified; done means those closures no longer trigger this rule while ordinary closure body length checks remain intact.