feat: redesign aggregate parameter input with improved UI (#7179)

# [Dashboard] Feature: Redesign Aggregate Parameter Input Component

## Notes for the reviewer

This PR completely redesigns the aggregate parameter input component with a more user-friendly interface. The new design uses a popover pattern instead of the previous MultiSelect approach, making it easier to view and select aggregation presets.

## How to test

1. Open any insight blueprint that uses aggregation
2. Click on the aggregate parameter input
3. Test searching for presets, selecting/deselecting options
4. Verify that manual text entry still works in the textarea
5. Check that the selected aggregations display correctly when the popover is closed

Author: catalyst17