Multiple language server processes increase memory footprint

**Describe the bug**

The extension spawns 2 copilot-language-server-arm64 processes per project, each consuming about 1GB of memory.
This increases memory pressure and leads to poor performance. Xcode's own high memory consumption doesn't make things better.
The fact that VS Code doesn't have this issue suggests that this is something that should be addressed.

**Versions**
- Copilot for Xcode: 0.46.0
- Xcode: 26.1.1
- macOS: 15.6.1

**Hardware**
- Apple M1 Pro 32 GB

**Steps to reproduce**
1. Open an Xcode project
2. Observe 2 copilot-language-server-arm64 processes spawning instantly
3. Open another project
4. Observe another 2 copilot-language-server-arm64 instances spawning
5. Close all the projects
6. Observe the copilot-language-server-arm64 processes remaining in memory

**Screenshots**