add a new plugin Pomodoro

[azarmadr]

Check-list

• [ ] There is a linked issue discussing the motivations for this feature or bugfix
• [ ] Unit tests have been added where possible
• [ ] I've added / updated documentation for any user-facing features.
• [ ] Performance seems to be comparable or better than current main

What this change is adding / fixing

Add a new plugin Pomodoro Clock, allowing user to use music as the timer to focus and take breaks. Includes a plugin sidebar to control/view the timer details. possible configurations are focus time, break time, long break time, and long break gap.