Dropdown remains open after focus is lost from `MultiSearch` component - keyboard accessibility

[spli02]

The dropdown remains open after MultiSearch component loses focus when navigating via keyboard. It opens as expected when the component receives focus, but it doesn't close when focus moves away using the Tab key.

Screencast.from.2025-06-13.08-42-39.mp4

[mkrause]

This should be fixed as part of #215

(Haven't had the time to finish this PR yet)

[spli02]

It also has an issue that user can't select any option from dropdown of MultiSearch component only by using keyboard (like pressing Tab or arrow key).