feat: improve WebSocket instance management on close event

- Added logic to remove the WebSocket instance from the plugin after a close event is received.
- Introduced a new static method `removeInstance` in `WebSocketPlugin` to handle instance removal.

Author: UnschooledGamer

src/plugins/websocket/src/android/WebSocketInstance.java

@@ -179,6 +179,8 @@ public void onClosed(@NonNull WebSocket webSocket, int code, @NonNull String rea
             Log.e(TAG, "Error creating close event", e);
         }
         sendEvent("close", closedEvent.toString(), false, false);
+        // remove instance after receiving close.
+        WebSocketPlugin.removeInstance(this.instanceId);
     }
 
     @Override

src/plugins/websocket/src/android/WebSocketPlugin.java

@@ -63,7 +63,6 @@ public void run() {
                             String error = inst.close(code, reason);
 
                             if(error == null) {
-                                instances.remove(instanceId);
                                 callbackContext.success();
                                 return;
                             } else if(!error.isEmpty()) {
@@ -124,4 +123,8 @@ public void onDestroy() {
         okHttpMainClient.dispatcher().executorService().shutdown();
         Log.i("WebSocketPlugin", "cleaned up... on destroy");
     }
+
+    public static void removeInstance(String instanceId) {
+        instances.remove(instanceId);
+    }
 }