Selector in SearchAutocompleteDropdown should memoize features

[graue]

I got this console warning from the selector in SearchAutocompleteDropdown:

Selector unknown returned a different result when called with the same parameters. This can lead to unnecessary rerenders. Selectors that return a new reference (such as an object or an array) should be memoized: https://redux.js.org/usage/deriving-data-selectors#optimizing-selectors-with-memoization