[Feature] [Android] Relocate the levels directory to storage (outside the app directory)

### Is your feature request related to a problem?

Prior to Android 11+, the `Android/data` directory cannot be accessed directly by the user via normal way (e.g opening it in file explorer).

### Describe the feature

Relocate the levels directory to a much accessible directory, e.g `AstroDX/levels`. Like how osu!droid did with how they import the chartmaps and skins.

### Reason for adding

I'm always frustated when trying to import charts into AstroDX, this requires me to move it via special access like Shizuku + Zarchiver or the normal `adb` way. This should help users who are on Android 11+ that are trying to import levels.

### Example(s)

We can take a reference to how osu!droid manages it's charts.

Note: `/sdcard` is where the storage is located.
```
/sdcard/osu!droid
└── Songs
└── 1233752 ALI - Wild Side (TV Size)
├── ALI - Wild Side (TV Size) (Ducky-) [Hard].osu
├── ALI - Wild Side (TV Size) (Ducky-) [Insane].osu
├── ALI - Wild Side (TV Size) (Ducky-) [Normal].osu
├── ALI - Wild Side (TV Size) (Ducky-) [Star].osu
├── audio.mp3
├── cyclone1.jpg
├── drum-hitnormal.wav
├── soft-hitclap.wav
├── soft-hitfinish.wav
├── soft-hitwhistle.wav
├── soft-sliderslide.wav
└── video.mp4
```

If we apply this to AstroDX, it would be like this.
```
/sdcard/AstroDX/
└── levels
├── category
│   ├── chart-1
│   │   ├── bg.png
│   │   ├── maidata.txt
│   │   └── track.mp3
│   └── chart-2
│   ├── bg.png
│   ├── maidata.txt
│   ├── pv.mp4
│   └── track.mp3
└── chart
├── bg.png
├── maidata.txt
└── track.mp3
```

### Additional context

_No response_