In Reminders screen: Implement the functionality to remind the users based upon the date and time, add new reminder

## Refer to the 'Reminders screen'
- Add functionality so that users can add reminders along with date and time
- Add functionality to remind users via a notification as per the date and time set by the user

Start by locating the Reminders screen and reading how reminder data is currently handled. Trace the existing screen flow before choosing the relevant entry points for date and time selection and notifications. Done means users can create a reminder with a date and time and receive a notification at the scheduled time.

Written by the indexing model from the issue text.