gpui: Add support for text in SVGs (#26335)

Closes #21319
Before: 

![image](https://github.com/user-attachments/assets/f75d7d59-75b1-4836-ae3b-6a1f526a5833)
After:

![image](https://github.com/user-attachments/assets/5fa28a6d-c417-4777-99f8-2a17edf759a0)

Use fontdb to load system fonts and pass it to resvg renderer. This adds
a small increase in startup time (around 30ms on my Linux system to
traverse fonts on a cold start). In the future once cosmic-text bumps
their version of fontdb we could clone the Database from
CosmicTextSystem

Release Notes: 
- Added: support for rendering text in SVGs