### Describe what your pull request does and which issue you’re targeting
Closes#928
This allows to select the time to switch between themes. The mentioned color/contrast problem with the time selection isn't fixed. I also simplified the settings code (0fe854fd49). And with [this](a590f5bc4c) GitNex hides the two options to change the time if your theme isn't `Auto (Light/Dark)` or `Auto (Retro/Dark)`. I could apply this also to the notifications settings, that means that the advanced settings for notifications (polling delay, light...) are hidden if the notifications aren't enabled.
this is ready to review/merge
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- [X] I carefully read the [contribution guidelines](https://codeberg.org/GitNex/GitNex/src/branch/main/CONTRIBUTING.md).
- [X] I'm following the code standards as defined [here](https://codeberg.org/gitnex/GitNex/wiki/Code-Standards).
- [X] By submitting this pull request, I permit GitNex to license my work under the [GNU General Public License v3](https://codeberg.org/GitNex/GitNex/src/branch/main/LICENSE).
Co-authored-by: qwerty287 <ndev@web.de>
Co-authored-by: M M Arif <mmarif@swatian.com>
Reviewed-on: https://codeberg.org/gitnex/GitNex/pulls/932
Reviewed-by: M M Arif <mmarif@noreply.codeberg.org>
Co-authored-by: qwerty287 <qwerty287@noreply.codeberg.org>
Co-committed-by: qwerty287 <qwerty287@noreply.codeberg.org>
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