[Android] Black Floccus splash screen

[sunjam]

Describe the feature you'd like to request

Papercut feature request. A black splash screen when starting Floccus for Android. I'm not sure of whether phone users use light themes... might be just me, but everything on my phone is dark mode.

• My nextcloud is also Dark Theme, which Nextcloud mobile apps usually match in color scheme.

Minor papercut, but that white splash screen is strong contrast to the otherwise dark themed app.

• Perhaps this can respect theme settings of the user's Nextcloud to be light or dark theme.

Describe the solution you'd like

Show black splash screen on Floccus for Android if you are on dark theme Nextcloud.

Describe alternatives you've considered

:dark_sunglasses: using the app as-is :white_check_mark: