[3.3.0-beta] "Dark mode" should use the same contrast for elements as in stable version

Description

Comparing the "Dark mode" in beta with the one in the stable version, the option elements use a different contrast color. This is harder to spot on a dark background while the color used in the stable version is more visible. It should be changed back to the color used in the stable.

Further suggestions:

• Use the same amount variable as in add to playlist dialog #1223 (closed) with a correct singular/plural form also in the Playlist view. Currently the Playlist view doesn't have a singular form at all: 1 tracks

• The option "Follow system mode" of the DayNight-mode is missing in the beginning wizard and this has to be changed manually at first start. It should be also choosable in the wizard.

Steps to reproduce

1. just switch to dark mode, scroll around and spot the too dark menu elements

Screenshots from beta version

Context

App version

3.3.0-beta