YouTube Playlist Support

### Issue Details

**Is your feature request related to a problem? Please describe.**
Yes, currently the AdGuard player on iOS allows playing **only one video at a time**. Once the video ends, the playback stops, and the user must manually navigate to select and play the next video. This disrupts the viewing experience, especially when watching a series of videos or listening to music.

**Describe the solution you'd like**
I propose adding a **"Custom Playlist"** or **"Add to Queue"** feature within the player.
The functionality should allow users to:
1. Create a list of videos (manually selected or via pasted links).
2. Enable **continuous playback**, where the app automatically plays the next video in the queue without user intervention.
3. Manage the queue (reorder or remove videos).

**Describe alternatives you've considered**
The only current alternative is manually opening links one by one, which is tedious and prevents a "hands-free" or continuous background listening experience.

**Additional context**
This feature would significantly enhance the app's utility as a privacy-focused media player, similar to how "Watch Later" playlists work on streaming platforms, but within the AdGuard environment.