Adapt signature of frontend methods.

[srobotta]

Hi @timhunt

During a run of behat tests I discovered that the signatore of two frontend methods have been changed. This causes a deprecation error:

019 Scenario: I can create a numerical question with an option to catch all student responses. # /selenium/moodle/public/mod/lesson/tests
/behat/all_other_answers_catch.feature:31
      And I am on the "Test lesson name" "lesson activity editing" page logged in as teacher1  # /srv/selenium.bfh.ch/moodle-5011/public/mod/lesson/tests
/behat/all_other_answers_catch.feature:25
        Exception: PHP errors found:
        Unknown error type: availability_quizquestion\frontend::allow_add(): Implicitly marking parameter $section as nullable is deprecated, the explici
t nullable type must be used instead at /selenium/moodle/public/availability/condition/quizquestion/classes/frontend.php: 77 in /selenium/moodle/public/lib/behat/classes/behat_session_trait.php:948
        Stack trace:
        #0 /selenium.bfh.ch/moodle-5011/public/lib/behat/classes/behat_session_trait.php(1158): behat_base->look_for_exceptions()
        #1 /selenium/moodle/public/auth/tests/behat/behat_auth.php(64): behat_base->execute()
        #2 /selenium/moodle/public/lib/behat/classes/behat_session_trait.php(1149): behat_auth->i_log_in_as()
        #3 /selenium/moodle/public/lib/tests/behat/behat_navigation.php(685): behat_base->execute()
        #4 /selenium/moodle/vendor/behat/behat/src/Behat/Testwork/Call/Handler/RuntimeCallHandler.php(110): behat_navigation->i_am_on_page_instance_logged_in_as()
...

The PR changes the signature of the two methods:

availability_quizquestion\frontend::allow_add()
availability_quizquestion\frontend::get_javascript_init_params()

to be in accordance with the parent.

Best regards, Stephan

PS. Moodle used for testing is 5.1.2, installed question_availability plugin: 2022092000