Donut Chart Migration to PatternFly 5

Migrated donut chart components from PatternFly 3/4 (C3.js-based) to PatternFly 5 (Victory Charts).

Changes:
- Replaced `patternfly-react` DonutChart with `@patternfly/react-charts` ChartDonut component
- Implemented `getDonutChartConfigPF5` service to transform data from C3 format to Victory format
- Updated event handling for click/hover interactions with proper cursor management
- Migrated tests from Enzyme to React Testing Library with behavior-based assertions
- Maintained support for all chart sizes (regular, medium, large) and configurations
- Preserved chart functionality: percentage display, tooltips, custom colors, search URL navigation

Technical details:
- Data transformation: `label, value, color` → `{x, y, name}` Victory format
- Updated configuration with PF5-specific properties (innerRadius, padding, colorScale)
- Removed deprecated props (unloadData)