Muhammad Adeel Tajamul

Added recent activity sort for course activity stats api (learners name and stats) Ticket Link: https://2u-internal.atlassian.net/browse/INF-474

Added username in bulk email optout event Ticket Link: [INF-1528](https://2u-internal.atlassian.net/browse/INF-1528)

feat: added notification grouping

2

## Description : Added grouping feature for new comment notifications ## Ticket https://2u-internal.atlassian.net/browse/INF-1472 

- Added `user_email` in `edx.ace.message_sent` and `edx.bulk_email.opt_out` - bulk_email event issue Ticket: [INF-1525](https://2u-internal.atlassian.net/browse/INF-1525)