Keep Python script limited to sysconfig usage (#511)

## Summary

This PR makes progress towards #476 and #479 by making the following
changes:
* Update the `ruff_server.py` script to limit itself to just getting the
Ruff binary path using `sysconfig`
* Use the `which` dependency and move the logic of locating the Ruff
binary from `PATH` to TypeScript
* Add log messages similar to `ruff-lsp`

## Test Plan

### 1

```json
{
  "ruff.nativeServer": true
}
```
Or
```json
{
  "ruff.nativeServer": true,
  "ruff.importStrategy": "fromEnvironment"
}
```

Logs:

When the `ruff` binary is installed in the current virtual environment:
```
2024-07-03 15:28:35.674 [info] Using the Ruff binary: /Users/dhruv/work/astral/ruff-vscode/.venv/bin/ruff
2024-07-03 15:28:35.675 [info] Server run command: /Users/dhruv/work/astral/ruff-vscode/.venv/bin/ruff server --preview
```

If there's no `ruff` binary in the current virtual environment:
```
2024-07-03 15:25:19.605 [info] Using the Ruff binary: /Users/dhruv/.local/bin/ruff
2024-07-03 15:25:19.606 [info] Server run command: /Users/dhruv/.local/bin/ruff server --preview
```

If the `ruff` binary is only available via `PATH`:
```
2024-07-03 15:32:12.172 [info] Using environment executable: /opt/homebrew/bin/ruff
2024-07-03 15:32:12.173 [info] Server run command: /opt/homebrew/bin/ruff server --preview
```

And, if there's no `ruff` binary anywhere on the system, use the bundled
binary:
```
2024-07-03 15:29:47.948 [info] Falling back to bundled executable: /Users/dhruv/work/astral/ruff-vscode/bundled/libs/bin/ruff
2024-07-03 15:29:47.948 [info] Server run command: /Users/dhruv/work/astral/ruff-vscode/bundled/libs/bin/ruff server --preview
```

### 2

```json
{
  "ruff.nativeServer": true,
  "ruff.importStrategy": "useBundled"
}
```

Logs:
```
2024-07-03 15:26:28.767 [info] Using bundled executable: /Users/dhruv/work/astral/ruff-vscode/bundled/libs/bin/ruff
2024-07-03 15:26:28.767 [info] Server run command: /Users/dhruv/work/astral/ruff-vscode/bundled/libs/bin/ruff server --preview
```

### 3

```json
{
  "ruff.nativeServer": true,
  "ruff.path": ["/Users/dhruv/work/astral/ruff/target/debug/ruff"]
}
```

Logs:
```
2024-07-03 15:27:42.342 [info] Using 'path' setting: /Users/dhruv/work/astral/ruff/target/debug/ruff
2024-07-03 15:27:42.342 [info] Server run command: /Users/dhruv/work/astral/ruff/target/debug/ruff server --preview
```

### 4

```json
{
  "ruff.nativeServer": true,
  "ruff.interpreter": [
    "/Users/dhruv/work/astral/ruff-lsp/.venv/bin/python"
  ]
}
```

Logs:
```
2024-07-03 15:35:23.578 [info] Using the Ruff binary: /Users/dhruv/work/astral/ruff-lsp/.venv/bin/ruff
2024-07-03 15:35:23.578 [info] Server run command: /Users/dhruv/work/astral/ruff-lsp/.venv/bin/ruff server --preview
```

### 5

What if the script failed? I modified the script path in TypeScript code
and we get the following logs:

```
2024-07-03 15:42:41.035 [error] Error while trying to find the Ruff binary: Error: Command failed: /Users/dhruv/work/astral/ruff-lsp/.venv/bin/python /Users/dhruv/work/astral/ruff-vscode/bundled/tool/find_ruff_binary_pat.py
/Users/dhruv/work/astral/ruff-lsp/.venv/bin/python: can't open file '/Users/dhruv/work/astral/ruff-vscode/bundled/tool/find_ruff_binary_pat.py': [Errno 2] No such file or directory

2024-07-03 15:42:41.037 [info] Using environment executable: /Users/dhruv/.local/bin/ruff
2024-07-03 15:42:41.040 [info] Server run command: /Users/dhruv/.local/bin/ruff server --preview
```

bundled/tool/find_ruff_binary_path.py

@@ -0,0 +1,35 @@
+import os
+import sys
+import sysconfig
+from pathlib import Path
+from typing import Optional
+
+RUFF_EXE = "ruff.exe" if sys.platform == "win32" else "ruff"
+
+
+def find_ruff_binary_path() -> Optional[Path]:
+    """Return the ruff binary path if it exists, `None` otherwise."""
+    bin_path = Path(sysconfig.get_path("scripts")) / RUFF_EXE
+    if bin_path.is_file():
+        return bin_path
+
+    if sys.version_info >= (3, 10):
+        user_scheme = sysconfig.get_preferred_scheme("user")
+    elif os.name == "nt":
+        user_scheme = "nt_user"
+    elif sys.platform == "darwin" and sys._framework:
+        user_scheme = "osx_framework_user"
+    else:
+        user_scheme = "posix_user"
+
+    scripts_path = Path(sysconfig.get_path("scripts", scheme=user_scheme)) / RUFF_EXE
+    if scripts_path.is_file():
+        return scripts_path
+
+    return None
+
+
+if __name__ == "__main__":
+    ruff_binary_path = find_ruff_binary_path()
+    if ruff_binary_path:
+        print(os.fsdecode(str(ruff_binary_path)), flush=True)

package.json

@@ -386,13 +386,15 @@
   "dependencies": {
     "fs-extra": "^11.1.1",
     "ovsx": "^0.7.1",
-    "vscode-languageclient": "^8.1.0"
+    "vscode-languageclient": "^8.1.0",
+    "which": "^4.0.0"
   },
   "devDependencies": {
     "@types/fs-extra": "^11.0.1",
     "@types/glob": "^8.1.0",
     "@types/node": "^20.3.1",
     "@types/vscode": "1.75.0",
+    "@types/which": "^3.0.4",
     "@typescript-eslint/eslint-plugin": "^5.59.2",
     "@typescript-eslint/parser": "^5.59.2",
     "@vscode/vsce": "^2.19.0",

src/common/constants.ts

@@ -44,16 +44,15 @@ export const DEBUG_SERVER_SCRIPT_PATH = path.join(
 );
 
 /**
- * Path to the Python script that starts the native language server with an
- * appropriate `ruff` executable.
+ * Path to the Python script that tries to find the Ruff binary path.
  *
- * This should only be used as a fallback if the user has not specified either
- * the `path` setting or is not using the bundled import strategy.
+ * This should only be used as a fallback if there is no valid `ruff` binary in
+ * the user's `path` setting or the import strategy isn't `useBundled`.
  */
-export const NATIVE_SERVER_SCRIPT_PATH = path.join(
+export const FIND_RUFF_BINARY_SCRIPT_PATH = path.join(
   BUNDLED_PYTHON_SCRIPTS_DIR,
   "tool",
-  "ruff_server.py",
+  "find_ruff_binary_path.py",
 );
 
 /**