feat(typeahead): add support for custom filter function

[valorkin]

Summary

• Add support for custom filter functions in typeahead directive
• Developers can now provide custom filtering logic via typeaheadFilterFunction input
• Function signature: (option: any, query: string) => boolean
• Maintains full backward compatibility with existing default filtering

Test plan

• [x] Custom filter function works with complex filtering logic
• [x] Default filtering still works when no custom filter provided
• [x] Unit tests cover custom filter functionality and edge cases
• [x] E2E tests verify behavior in real browser environment
• [x] No regressions in existing typeahead functionality

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