Automation: ensure the focus effect on the selected option in the namespace filter is visible.

[gaktive]

Based on work done in #7757, let's write an automated test to check that the highlighted option in the namespace filter dropdown isn't invisible.

This dropdown is also used in a few other places, such as the burger menu --> Global Settings --> Performance --> enable Require Namespace Filtering and reduce threshold. Previously, the focus effect on the selected option didn't change the font and icon colours.

@bisht-richa can offer guidance based on her work there.

To Reproduce

• Click on Namespace filter and choose an option.

Result
Focus effect on the selected option doesn't change the font and icon colours.

Expected Result

Focused option should be clearly distinguishable from the other ones.

[cnotv]

This is again completely a cosmetic test which requires a new definition in order to be tested.