TypeBodyLengthRule should not count conditional directives

New Issue Checklist

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

Describe the bug

type_body_length rule counts lines with conditional directives as lines of code, which is not correct. Example:

class Test {
  func foo() {
    #if DEBUG
    print("test")
    #endif 
  }
}

How many lines are in foo function? swiftlint thinks there are 5 lines, but there's 3 lines of code.
This rule ignores comments and whitespaces already since they are not an actual lines of code (#369). So, why a conditional directives does count?
I believe it's an incorrect rule behaviour.

Environment

• SwiftLint version (run swiftlint version to be sure)?
  0.39.1
• Installation method used (Homebrew, CocoaPods, building from source, etc)?
  CocoaPods

swiftlint ouptut for sample above:

$ pbpaste | swiftlint lint --no-cache --use-stdin --enable-all-rules
Loading configuration from '.swiftlint.yml'
<nopath>:1:1: warning: Type Body Length Violation: Type body should span 3 lines or less excluding comments and whitespace: currently spans 4 lines (type_body_length)

using sample yml:

type_body_length: 3

Start with the TypeBodyLengthRule entry point and reproduce the reported result using the SwiftLint stdin command and sample configuration from the issue. The work is done when conditional directives are excluded from the counted lines while comments and whitespace remain excluded, and the sample reports the expected three lines.