feat(core-select): adding occupation-category directive

[thomas-lg]

Description

Adds a new LuCoreSelectOccupationCategoriesDirective to provide occupation category selection for simple and multi selects. It fetches data from the /organization/structure/api/occupation-categories endpoint and supports filtering and sorting.

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This introduces a new directive for selecting occupation categories. It also adds mock data for the API endpoint in the storybook environment.