ISSUE-5201: Removes splitting of string while setting default course tools.
ISSUE-5201: Updates db while upgradation when splitting of string is removed when setting default course tools.
ISSUE-5201: Run SQL qyery only if home_defaults_2 or main_defaults_2 exists
ISSUE-5201: Adding a new class file mods/_core/modules/classes/ModuleUtility.class.php for extracting and sharing code in mods/_core/courses/admin/default_mods.php and mods/_core/modules/default_mods.php as they share similar code and logic.
ISSUE-5201: Eliminating code duplication by creating a function