Features Brave should copy from uBO

In uBO you can see content of each filter and number of rules each filter have.

Also uBO has this function which automatically detects duplicate filter rules and disables redundant ones.

Please implement these features to Brave.

Use the uBO behavior described in the issue as the reference, since no repository files, tests, or entry points are named. First locate the engine code and existing tests for filter inspection and rule deduplication; the work is complete when both behaviors are implemented and covered by tests matching the requested uBO functionality.

Written by the indexing model from the issue text.