In `new_statistic.dart`, updated the onTap function for a GestureDetector to clear old content before adding new content to the list.
In `new_statistics_state.dart`, added a line to clear the contents list before adding new content to it.
In `stat_cats_general_state.dart`, added a few lines to clear the contents list before adding new content to it.
- Add listener for theme change in NewStatisticState
- Move statistic categories to NewStatisticState and update StatMenuItemType to use Assets.dart
- Update NewStatisticCategories to use statCat from NewStatisticState
- Add refresh method in NewStatisticState to update statCat list
- Call refresh method in initState of _NewStatisticState to update statCat list on theme change
* Updated dependencies to their latest versions
* Removed unused imports in various files
* Changed textScaleFactor to TextScaler.linear in some files
* Fixed some formatting issues
No functional changes.