…tion

Support multiple Impersonate-Group subprotocols on WebSocket connections.
Maintains backward compatibility for single-group impersonation.

…nation

Handle X-Console-Impersonate-Groups header by splitting comma-separated
groups into multiple Impersonate-Group headers for Kubernetes API.

Update GraphQL context to support array-valued headers for multi-group
impersonation. Change headers type from map[string]string to map[string]interface{}
to support both single string values and []string arrays.

Update fetch utilities to handle multi-group impersonation:
- Support array-valued Impersonate-Group headers
- Convert array to X-Console-Impersonate-Groups for fetch() API compatibility
- Add UserWithGroups kind support in header generation

…ation

Add multi-group support to Redux actions:
- Update startImpersonate to accept groups parameter
- Encode multiple groups as WebSocket subprotocols in UserWithGroups mode
- Pass groups to beginImpersonate action
- Expose store and UIActions for testing (temporary)

Add modal component for multi-group user impersonation:
- TypeScript React component with group selection
- Multi-select group input with search/filter
- Chip display for selected groups
- Form validation for username
- Internationalization support

Integrate multi-group impersonation into the UI:
- Update impersonation banner to display multiple groups
- Add modal trigger in masthead toolbar
- Update user component to show impersonated user
- Add feature flag checks in app component
- Add masthead menu items for start/stop impersonation
- Add enabled parameter to usePackageManifestCheck hook

…nges-combined

… in the multi-group impersonation modal.