Feature Request: Enable Directory Support for yr fmt

[r0ny123]

The yr fmt command currently accepts only files as arguments for formatting YARA rules. On the other hand, the yr check command supports both files and directories, enabling bulk processing of YARA rules. It would be helpful if yr fmt also supported directories to allow bulk formatting of YARA rules, similar to yr check.

Also, provide an optional flag (e.g., -d or --max-depth) to specify recursion depth, similar to yr check.