Add type hints and refactor LastFm cog

## **__LastFM Cog Update__**

### Basic Rundown of Update
This update brings improved error handling, more robust server-wide commands, and a better developer experience for the LastFM cog!

```
Hey devs!
This update makes your Last.fm Discord bot more reliable and user-friendly.
Enjoy smoother server-wide stats and less crashing on API hiccups.
Keep scrobblin'! 🎶
```

### Notable Changes to Big Commands
- `.fmservertop` and `.fmleaderboard` now run much faster and handle errors gracefully.
- All commands now provide clearer error messages for users.

---

### **Feature 1: Enhanced Error Handling**
- All commands now catch and report Last.fm API/network errors.
- Users get friendly feedback if something goes wrong, not just a traceback.

### **Feature 2: Async Server Stats**
- Server-wide commands fetch data for all users in parallel (asyncio.gather).
- Typing indicators show while stats are loading.

### **Feature 3: Rate Limit Friendly**
- Small delays added to avoid hitting Last.fm API rate limits.

---

### __Bug Fixes__
- Fixed: Server-wide commands no longer fail silently if one user errors.
- Fixed: All commands now check for missing accounts and handle gracefully.
- Fixed: Emoji setting now checks for permission errors and invalid emojis.

Author: rustybusgaming