Use execFile rather than spawn (#544)

## Summary

Recommended in #539.

src/common/server.ts

@@ -38,7 +38,7 @@ import {
 import { updateServerKind, updateStatus } from "./status";
 import { getProjectRoot } from "./utilities";
 import { isVirtualWorkspace } from "./vscodeapi";
-import { spawn } from "child_process";
+import { execFile } from "child_process";
 import which = require("which");
 
 export type IInitializationOptions = {
@@ -49,40 +49,23 @@ export type IInitializationOptions = {
 /**
  * Function to execute a command and return the stdout.
  */
-function executeCommand(cmd: string, args: string[] = []): Promise<string> {
+function executeFile(file: string, args: string[] = []): Promise<string> {
   return new Promise((resolve, reject) => {
-    const child = spawn(cmd, args);
-
-    let stdout = "";
-    let stderr = "";
-
-    child.stdout.on("data", (data) => {
-      stdout += data.toString();
-    });
-
-    child.stderr.on("data", (data) => {
-      stderr += data.toString();
-    });
-
-    child.on("close", (code) => {
-      if (code !== 0) {
-        reject(new Error(stderr));
+    execFile(file, args, (error, stdout, stderr) => {
+      if (error) {
+        reject(new Error(stderr || error.message));
       } else {
         resolve(stdout);
       }
     });
-
-    child.on("error", (error) => {
-      reject(error);
-    });
   });
 }
 
 /**
  * Get the version of the Ruff executable at the given path.
  */
 async function getRuffVersion(executable: string): Promise<VersionInfo> {
-  const stdout = await executeCommand(executable, ["--version"]);
+  const stdout = await executeFile(executable, ["--version"]);
   const version = stdout.trim().split(" ")[1];
   const [major, minor, patch] = version.split(".").map((x) => parseInt(x, 10));
   return { major, minor, patch };
@@ -131,7 +114,7 @@ async function findRuffBinaryPath(
   // Otherwise, we'll call a Python script that tries to locate a binary.
   let ruffBinaryPath: string | undefined;
   try {
-    const stdout = await executeCommand(settings.interpreter[0], [FIND_RUFF_BINARY_SCRIPT_PATH]);
+    const stdout = await executeFile(settings.interpreter[0], [FIND_RUFF_BINARY_SCRIPT_PATH]);
     ruffBinaryPath = stdout.trim();
   } catch (err) {
     await vscode.window