Use Composer to pull in required modules

Problem/Motivation

Currently opigno_ilt requires the following:

- opigno_calendar_event:opigno_calendar_event
- popup_field_group:popup_field_group
- opigno_learning_path:opigno_learning_path

However on install, these modules may not be present in the codebase.

Proposed resolution

Add modules to composer.json require.