def untracked?(file)
      case_aware_include?(:untracked, :lc_untracked, file)
    end
Determines whether the given file has is tracked by git.
File path starts at git base directory

@param file [String] The name of the file.
@example Check if lib/git.rb is an untracked file.
untracked?('lib/git.rb')
@return [Boolean]