Feature: Add basic support for DJI drone import

Enable the import from DJI drone sd-cards similar to the GoPro media.

Since there is no version text file on the sd-cards of DJI drones, it requires some directory/filename logic to identify as a DJI drone.

Won't be able to recognize the drone type or serial number, but at least the fact that it is DJI drone media.

```
➜ tree -d
.
├── DCIM
│   └── 100MEDIA
├── LOST.DIR
└── MISC
├── GIS
├── IDX
└── THM
└── 100

9 directories
```

```
➜ MISC tree
.
├── GIS
│   └── dji.gis
├── IDX
├── IDX_BLOCK
└── THM
└── 100
├── DJI_0001.SCR
├── DJI_0001.THM
├── DJI_0002.SCR
├── ...
├── DJI_0524.THM
├── DJI_0525.SCR
└── DJI_0525.THM
```