Allow mutant:disable to apply to inline macros and visibility modifiers

[dgollahon]

class MutantExample
  private

  # mutant:disable
  public def demo
    {}.freeze
  end
end

RSpec.describe MutantExample do
  it 'is a hash' do
    expect(described_class.new.demo).to be_a(Hash)
  end
end

The above produces an alive mutation (see #1398) but if I change the public modifier to not be inline, the mutant:disable does work:

class MutantExample
  private

  # mutant:disable
  def demo
    {}.freeze
  end
  public :demo
end

Note that I care about this beyond just private, protected, and public. I have some macros (like memoize) where I would prefer to use it in an inline fashion rather than repeating the name of the method below the method in the macro.