Fix performance in get resources ui

[Sebastian-ubs]

Describe the bug
As found in #1399, there is some unexpected delay when

• opening the language filter popover in get resources
• filtering down the list of installed resources

Opening the language filter popover takes >1 seconds, so that it feels unresponsive and user might click again, which would close the popover.

Filtering resources is done on every keystroke without a debounce. As javascript is single threaded, filtering down the list causes a lagging in showing the typed characters in the search input.

To Reproduce
Steps to reproduce the behavior:

1. Click "Home" or "Open" from the main menu
2. [Click the "Get resources" button] (this will be the future implementation, currently Home will already open "get resources")
3. Follow description above

Expected behavior
The get resources ui should feel responsive

Implementation ideas
Check if always rendering the language filter popover and make it hidden / non-hidden is more performant.
Debouncing the search might help.