Add the program method if the source of the script file doesn't match the source of all program methods in the file

[ono-max]

The current test generator adds just the scenario method when the generated file already exists. However, users want to add the program method if the source of the script file doesn't match the source of all program methods. This PR fixes it.

Before

    def test_1635256878
      debug_code(program) do
        type 's'
        assert_line_num 2
        assert_line_text([
          /\[1, 10\] in .*/,
          /     1\| module Foo/,
          /=>   2\|   class Bar/,
          /     3\|     def self\.a/,
          /     4\|       p 'hoge'/,
          /     5\|       "hello"/,
          /     6\|     end/,
          /     7\|   end/,
          /     8\|   Bar\.a/,
          /     9\|   bar = Bar\.new/,
          /    10\| end/,
          /=>\#0\t<module:Foo> at .*/,
          /  \#1\t<main> at .*/
        ])
        type 'q!'
      end
    end

After

class FooTest1635256743 < TestCase
    def program
      <<~RUBY
         1| module Foo
         2|   class Bar
         3|     def self.a
         4|       p 'hoge'
         5|       "hello"
         6|     end
         7|   end
         8|   Bar.a
         9|   bar = Bar.new
        10| end
      RUBY
    end
    
    def test_1635256743
      debug_code(program) do
        type 's'
        assert_line_num 2
        assert_line_text([
          /\[1, 10\] in .*/,
          /     1\| module Foo/,
          /=>   2\|   class Bar/,
          /     3\|     def self\.a/,
          /     4\|       p 'hoge'/,
          /     5\|       "hello"/,
          /     6\|     end/,
          /     7\|   end/,
          /     8\|   Bar\.a/,
          /     9\|   bar = Bar\.new/,
          /    10\| end/,
          /=>\#0\t<module:Foo> at .*/,
          /  \#1\t<main> at .*/
        ])
        type 'q!'
      end
    end
  end