Course formats: Add function format_base::default_blocks() to replace config.php

The test is aimed to test that nothing is changed: Test 1 - creating courses. Login as course manager (not admin but with capability to create courses) Create one course of each core format, make sure all default blocks are added. Add $CFG->defaultblocks_override with the list of blocks there Create courses, make sure that blocks from format config are ignored Add $CFG->defaultblocks_topics with the list of blocks there Create course with 'topics' format, make sure that blocks from format config are ignored Test 2 - creating moodle site Create fresh installation of moodle site Make sure that default blocks are added to the front page: see code of function blocks_get_default_site_course_blocks()