[Feature Request]: Customized theme for Light and Dark mode when System default theme is picked

### Guidelines

- [x] I have [searched the issue tracker for open and closed issues](https://github.com/FreeTubeApp/FreeTube/issues?q=is%3Aissue+sort%3Arelevance-desc) that are similar to the feature request I want to file, without success.
- [x] I have searched the [documentation](https://docs.freetubeapp.io/) for information that matches the description of the feature request I want to file, without success.
- [x] This issue contains only one feature request.
- [x] I have read and agree to follow the [rules](https://docs.freetubeapp.io/community/rules/).

### Problem Description

Current System default theme uses the default light and dark mode not allowing for customizations

### Proposed Solution

Allow to select what theme will be loaded on light and dark mode

### Alternatives Considered

if possible, can we use `black theme` for the dark mode

### Issue Labels

visual improvement, improvement to existing feature

### Additional Information

The idea was from Android Studio/Intellij. It enables you to select what theme will picked when the OS is on light/dark mode

I honestly want `Black` theme for the dark mode of `System Default` Theme