fix: compatible with old version egg-core package name (#38)

egg-bin v6 版本启动项目时，[无法读到 cluster.listen.port
的配置](eggjs/bin#280)

原因是 [egg-bin 6.13.0](eggjs/bin#278) 版本引入了
egg-utils v4，而 v4 在查找 egg-core 包时，包名从写死的 `egg-core` 改成了 `@eggjs/core`，如果
eggjs 版本没跟上，子依赖 egg-core 没升级，egg-utils 就会查找失败

<img width="2069" alt="截图_280f31b0-8db9-4fa3-9fdc-a17975625c5e"
src="https://github.com/user-attachments/assets/d6b91d54-0ea3-4733-b9aa-a03e9aac1621"
/>


一种可能的解决方法是同时查找两个包名，如 PR 内容所示

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **Bug Fixes**
	- Improved module import logic for the Egg framework
- Enhanced backward compatibility with different module naming
conventions
	- Streamlined error handling for module imports

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: rrbe

src/plugin.ts

@@ -133,30 +133,35 @@ async function findEggCore(options: LoaderOptions): Promise<{ EggCore?: object;
     debug('[findEggCore] import "egg" from paths:%o error: %o', paths, err);
   }
 
-  const name = '@eggjs/core';
-  // egg => egg-core
-  try {
-    const { EggCore, EggLoader } = await importModule(name, { paths });
-    if (EggLoader) {
-      return { EggCore, EggLoader };
+  // egg-core 在 6.2.3 版本中更名为 @eggjs/core，为兼容老版本，支持同时查找两个包，优先使用新名字
+  const names = [ '@eggjs/core', 'egg-core' ];
+  for (const name of names) {
+    try {
+      const { EggCore, EggLoader } = await importModule(name, { paths });
+      if (EggLoader) {
+        return { EggCore, EggLoader };
+      }
+    } catch (err: any) {
+      debug('[findEggCore] import "%s" from paths:%o error: %o', name, paths, err);
     }
-  } catch (err: any) {
-    debug('[findEggCore] import "%s" from paths:%o error: %o', name, paths, err);
-  }
 
-  try {
-    const { EggCore, EggLoader } = await importModule(name);
-    if (EggLoader) {
-      return { EggCore, EggLoader };
+    try {
+      const { EggCore, EggLoader } = await importModule(name);
+      if (EggLoader) {
+        return { EggCore, EggLoader };
+      }
+    } catch (err: any) {
+      debug('[findEggCore] import "%s" error: %o', name, err);
     }
-  } catch (err: any) {
-    debug('[findEggCore] import "%s" error: %o', name, err);
-  }
 
-  let eggCorePath = path.join(options.baseDir, `node_modules/${name}`);
-  if (!(await exists(eggCorePath))) {
-    eggCorePath = path.join(options.framework, `node_modules/${name}`);
+    let eggCorePath = path.join(options.baseDir, `node_modules/${name}`);
+    if (!(await exists(eggCorePath))) {
+      eggCorePath = path.join(options.framework, `node_modules/${name}`);
+    }
+    if (await exists(eggCorePath)) {
+      return await importModule(eggCorePath);
+    }
   }
-  assert(await exists(eggCorePath), `Can't find ${name} from ${options.baseDir} and ${options.framework}`);
-  return await importModule(eggCorePath);
+
+  assert(false, `Can't find ${names.join(' or ')} from ${options.baseDir} and ${options.framework}`);
 }