MDL-68806 quiz: Retain backwards compatibility in external functions

To ensure backwards compatibility, particularly with the mobile app, the
mod_quiz_get_user_attempts and mod_quiz_get_attempt_review functions
will continue to return only the existing 'inprogress', 'overdue',
'finished' and 'abandoned' states for quiz attempts.

'submitted' attempts will be reported as 'finished', while 'notstarted'
attempts will be reported as 'inprogress'.

These functions are now deprecated. The new functions
mod_quiz_get_user_quiz_attempts and mod_quiz_get_quiz_attempt_review
will replace them. They have exactly the same code as the original
functions had before these changes, so will return all attempts in their
true states.