Add Queue Time Metrics for All Detected Queues

[philip-C96]

Hi @danihodovic and contributors,
This is my first-ever pull request, so please bear with me if I miss anything—I'm open to feedback! I aimed to address the issue where celery-exporter doesn't expose queue time metrics. I implemented queue time metrics for celery-exporter to track the latency between task receipt and task start for all detected queues, inspired by Grafana's celery-exporter. To achieve this, I used Claude, to help replicate the metric logic (just want to be clear i vibe code it), which I carefully reviewed to ensure compatibility with the project. The implementation uses cachetools.LRUCache to store task receive timestamps, calculates latency on the task-started event, and removes the task ID from the cache to manage memory.