Collect user feedbacks

In order to understand how our model is performing in real-world, add user feedback option. Collect these feedbacks as a signal to understand when to retrain our model.

Lab by full_stack_deep_learning: [colab notebook](https://colab.research.google.com/github/full-stack-deep-learning/fsdl-text-recognizer-2022-labs/blob/main/lab08/notebooks/lab08_monitoring.ipynb)

No implementation files or entry points are named; start with the linked Full Stack Deep Learning monitoring notebook and then locate the repository component handling model requests. Define how users submit feedback and how those feedbacks become a retraining signal; done should include a clear feedback path and documented signal behavior.

Written by the indexing model from the issue text.