feat(Partners): enhance BusinessFieldFilter with grouped display

[Ysrbolles]

Extending the business field values to hold both a category and the business field itself. Something like:

• Transport / Train
• Transport / Aviation
• Accommodation / Hotel
• Accommodation / Holiday-Home
• etc

With the purpose to show this in the frontend grouped by the first field like "Transport" "Accommodation" and have the 2nd part as selectable filter criteria to search for businesses which have for instance "Transport / Train" selected.

[Ysrbolles]

feat(BusinessFieldFilter): add category-level toggling for business fields

• Made category headers clickable, allowing users to toggle the active state of all fields within a category in the BusinessFieldFilter component.
• Updated reducer with a new action TOGGLE_CATEGORY to handle toggling all fields in the selected category when the header is clicked.
• Preserved the existing styles for category headers and individual fields.

This update improves usability by enabling easier selection of grouped business fields.