This PR fixes issue of incorrect LSP path args caused by using a
relative path when customizing data directory.
command:
```bash
.\target\debug\zed.exe --user-data-dir=.\target\data
```
before:
```log
2025-07-29T14:17:18+08:00 INFO [lsp] starting language server process. binary path: "F:\\nvm\\nodejs\\node.exe", working directory: "F:\\zed\\target\\data\\config", args: [".\\target\\data\\languages\\json-language-server\\node_modules/vscode-langservers-extracted/bin/vscode-json-language-server", "--stdio"]
2025-07-29T14:17:18+08:00 INFO [project::prettier_store] Installing default prettier and plugins: [("prettier", "3.6.2")]
2025-07-29T14:17:18+08:00 ERROR [lsp] cannot read LSP message headers
2025-07-29T14:17:18+08:00 ERROR [lsp] Shutdown request failure, server json-language-server (id 1): server shut down
2025-07-29T14:17:43+08:00 ERROR [project] Invalid file path provided to LSP request: ".\\target\\data\\config\\settings.json"
Thread "main" panicked with "called `Result::unwrap()` on an `Err` value: ()" at crates\project\src\lsp_store.rs:7203:54
cfd5b8ff10/src/crates\project\src\lsp_store.rs#L7203 (may not be uploaded, line may be incorrect if files modified)
```
after:
```log
2025-07-29T14:24:20+08:00 INFO [lsp] starting language server process. binary path: "F:\\nvm\\nodejs\\node.exe", working directory: "F:\\zed\\target\\data\\config", args: ["F:\\zed\\target\\data\\languages\\json-language-server\\node_modules/vscode-langservers-extracted/bin/vscode-json-language-server", "--stdio"]
```
Release Notes:
- N/A
2fced602b8