feat: add data dir option

ews_client.ts

@@ -3,13 +3,18 @@ import fs from "node:fs";
 import https from "node:https";
 import { createRequire } from "node:module";
 import path from "node:path";
-import { fileURLToPath } from "node:url";
 import { promisify } from "node:util";
 import type { Email } from "./types/email.ts";
 import type { Folder } from "./types/folder.ts";
 import type { LoginConfig } from "./types/login_config.ts";
 
 let inMemoryPassword: string | null = null;
+let dataDir: string = "./data";
+
+export function initDataDir(dir: string): void {
+  dataDir = path.resolve(dir);
+  fs.mkdirSync(dataDir, { recursive: true });
+}
 
 export function setPassword(password: string): void {
   inMemoryPassword = password;
@@ -74,8 +79,7 @@ ${body}
 }
 
 function configFilePath(): string {
-  const dir = path.dirname(fileURLToPath(import.meta.url));
-  return path.join(dir, "config.json");
+  return path.join(dataDir, "config.json");
 }
 
 export function loadConfig(): LoginConfig {