For activity based course completion criteria allow instant
course completion updates if the activity completion state was changed
for a single user.

jun authored Mar 30, 2021 and Shamim Rezaie committed Apr 22, 2021

* *_get_completion_state() callback functions have been deprecated and
should no  longer be used. Plugins that define custom completion rules
must implement the mod_[modname]\completion\custom_completion class that
extends the \core_completion\activity_custom_completion base class.

* activity_completion_condition_displayed_as()
  - Shows the status of an automatic completion condition for a given
    activity
* activity_should_have_the_completion_condition()
  - Checks that the activity displays the given completion condition
* manual_completion_button_displayed_as()
  - Shows the status of the manual completion button for a given
    activity
* the_manual_completion_button_for_activity_should_be_disabled()
  - Checks that the manual completion button for the given activity is
    disabled.
* there_should_be_no_completion_for_activity()
  - Checks that the activity does not show completion information
* toggle_the_manual_completion_state()
  - Toggles the manual completion button's state for a given activity
* overridden_manual_completion_button_displayed_as()
  - Checks the manual completion state of an activity.
* overridden_activity_completion_condition_displayed_as()
  - Checks if the activity with specified name is maked as complete.