fix restarting bot by killing all child processes of bot (#2861)

Calling `child_process.kill()` will kill that process but does not kill all processes spawned by that process. We need to run the bot in a detached process which gets its own process group, then call `process.kill(-child.pid)` to kill all porcesses in that group.

Composer/packages/extensions/plugin-loader/src/composerPluginRegistration.ts

@@ -38,9 +38,8 @@ export class ComposerPluginRegistration {
     this._description = val;
   }
 
-  // eslint-disable-next-line @typescript-eslint/no-explicit-any
-  public log(message: string, ...args: any[]) {
-    this._log(message, ...args);
+  public get log() {
+    return this._log;
   }
 
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