[FEATURE] Option in setup or welcome app to change SDDM Theme

[nfowlie]

Is your feature request related to a problem? Please describe. After using the ml4w setup script and installing the SDDM Theme Sequoia I am unable to change to another SDDM theme via the KDE SDDM settings. After applying a new theme it reverts to using Sequoia.

Describe the solution you'd like During the setup script allow for choosing an SDDM theme from already installed options. Also adding a place in the welcome app to change the theme post setup would be desirable.

Describe alternatives you've considered Allow the SDDM to be changed via the the KDE SDDM settings screen.

Additional context Unsure if this is new to this version or if this is caused by me selecting the Sequoia install from the setup script.