[Feature/Improvement] Smart Watch Notifications

**Purpose:** As a user, I would like to receive notifications when starting/ending an excercise. I would like to see this notification in my smartwatch / band.

**More details:** I would like to receive a notification at the same time the whistle sound in the app saying what exercise I am in, if it is the middle point or if the resting part starts.

**Acceptance Criteria:** Receive a notification with the title of the part that is starting. Also a notification at the end of the routine.