Refactor and enhance diagram and branching logic UI

Refactored and reformatted code for improved readability and maintainability:
- Updated `MudSlider` for zoom functionality.
- Improved diagram scaling transitions and added null checks.
- Enhanced conditional branching logic for `TrueFalse` and options.
- Introduced scoped variable for question group handling.
- Added `StateHasChanged()` for better UI updates.
- Updated `SfDiagramComponent` property with getter and setter.

No functional changes except for added robustness and smoother UI transitions.

Author: David Warwick