[Feature/Improvement] Add more colors for color coding timers

**Purpose:** As a user, I would like to have a variety of colors to choose from to color code my timers.

**More details:**

The current color picker uses the material defaults which is a limited selection. Additionally, some of the colors are too light against the default font color as pictured in the screenshot below.

Use the [Custom Colors feature](https://pub.dev/packages/flutter_material_color_picker#custom-colors) of the material color picker to set a list of colors that contrast well against the default font color. Aim for no more than 40, at least 25.

Suggested colors:

1. Colors.red,
2. Colors.red[900]
3. Colors.redAccent[700]
4. Colors.deepOrange,
5. Colors.deepOrange[900]
6. Colors.orange,
7. Colors.orange[900]
8. Colors.amber,
9. Colors.yellowAccent[700]
11. Colors.lime[900]
12. Colors.limeAccent[700]
14. Colors.green[900]
15. Colors.greenAccent[700]
16. Colors.teal,
17. Colors.tealAccent[700]
18. Colors.cyan,
19. Colors.cyanAccent[700]
20. Colors.lightBlue,
21. Colors.blue,
22. Colors.blue[900]
23. Colors.indigo,
24. Colors.indigoAccent[700]
25. Colors.deepPurple,
26. Colors.deepPurpleAccent,
27. Colors.purple,
28. Colors.purple[700]
29. Colors.purpleAccent[700]
30. Colors.pink,
31. Colors.pink[900]
32. Colors.brown,
33. Colors.grey,
34. Colors.blueGrey,
35. Colors.black

**Acceptance Criteria:**
- There are at least 25 colors to choose from and no more than 40.
- All selectable colors contrast well against the default font color.