Add edit buttons for timer widget
Up/down buttons for each timer's sections allow for easy modification of time by 1h, 1min and 1s similar to SpinBox. Those buttons are implemented using new button type - SvgButton.
- Add control buttons below main widget for start, stop and reset timer.
- Improve add button in settings page of predefined timers.
FEATURE: 397841 FIXED-IN: 5.21