Add option to clear config cache

Loaded configs are stored in LRU cache (utils/data.py). Modifying a config at runtime will result in changes which only become active once the particular config is reloaded from file (only if cache is too full to keep it), an option should clear the config cache.

Start in utils/data.py, where loaded configs are stored in the LRU cache, and trace how configs are retrieved and reloaded. Add an option to clear that cache so runtime config changes take effect without waiting for eviction. Done means the cache can be explicitly cleared and subsequent loads reflect the updated file.

Written by the indexing model from the issue text.