feat: enable ts support by process.env.EGG_TS_ENABLE = true (#43)

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

## Summary by CodeRabbit

- **New Features**
- **Expanded TypeScript Support Detection:** The application now checks
an additional configuration option to determine TypeScript support. This
enhancement provides a more reliable activation process for TypeScript
projects.
- **Enhanced Logging:** Diagnostic output has been improved to display a
more comprehensive summary of the configuration settings, making it
easier to trace and verify support conditions.

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

Author: fengmk2

src/import.ts

@@ -40,9 +40,10 @@ let _supportTypeScript: boolean | undefined;
 export function isSupportTypeScript() {
   if (_supportTypeScript === undefined) {
     const extensions = getExtensions();
-    _supportTypeScript = extensions['.ts'] !== undefined || process.env.VITEST === 'true';
-    debug('[isSupportTypeScript] %o, extensions: %j, process.env.VITEST: %j',
-      _supportTypeScript, Object.keys(extensions), process.env.VITEST);
+    // enable ts by process.env.EGG_TS_ENABLE or process.env.VITEST
+    _supportTypeScript = extensions['.ts'] !== undefined || process.env.VITEST === 'true' || process.env.EGG_TS_ENABLE === 'true';
+    debug('[isSupportTypeScript] %o, extensions: %j, process.env.VITEST: %j, process.env.EGG_TS_ENABLE: %j',
+      _supportTypeScript, Object.keys(extensions), process.env.VITEST, process.env.EGG_TS_ENABLE);
   }
   return _supportTypeScript;
 }