Java Edition Friends menu incorrectly has the non-selected tab darkened

When opening the friends menu in either the title screen or pause menu, the "Requests" tab is darkened until hovering over the tab. When clicking on it, the Friends tab is instead darkened. Since these textures use the default button textures (albeit separate textures), this makes it seem like the tab is disabled. There are two ways to solve this issue.

1. Either make it so the darkened button texture is used for the currently selected tab, so the other tab appears to be clickable. This can be as simple as swapping the `button` and `button_disabled` textures.

2. Change the buttons into tabs instead. This was done for the Create New World screen during 1.19.4's development, and it make it more clear what was being selected and what could be selected.