Show selected users at top in filter dropdowns

[dwstyagi]

Problem

Selected users in filter dropdowns were buried in alphabetical order, making it hard to see/manage current selections.

Solution

Added #reorderItems() method to multi_selection_combobox_controller.js that reorders DOM elements based on selection state. Called on connect() and after each #toggleSelection().

Test plan

• Open "Assigned to..." filter, select users --> they move to top
• Unselect a user --> they move back to alphabetical position
• Repeat for "Added by..." and "Closed by..."

Summary

• Filter dropdowns now show selected users at the top (sorted alphabetically)
• Unselected users appear below (also sorted alphabetically)
• Exclusive items like "No one" stay at the very top