Closes https://github.com/zed-industries/zed/issues/14334, allowing
users to set environment variables for a language server binary like:
```json
"lsp": {
"rust-analyzer": {
"binary": {
"path": "/Users/dbarsky/.cargo/bin/rust-analyzer",
"env": {
"RA_PROFILE": "*>100"
}
},
}
}
```
The newly introduced environment variables are merged with the shell
environment. Perhaps more controversially, I've _also_ removed the
trimming/`stderr:`-prefixing of language server logs. This because
rust-analyzer has some nice, tree-shaped profiling built-in, and it
prevents us from printing profiles like this:
<details>
<img width="1147" alt="Screenshot 2025-03-20 at 12 09 14 PM"
src="https://github.com/user-attachments/assets/b7066651-6394-492b-b745-906c66d3c7b2"
/>
</details>
Release Notes:
- Added the ability to set a language server's environment variables.
- Removed the `stderr`-prefix of a language server's stderr logs.
7ade7d8e45