Need "min_dims" validation rule

Under image upload validation rules, we dont have validation rule to check minimum height and width of uploading images. We only have "max_dims". Its great we can have a rule like min_dims.

Sounds like a great feature for your first contribution

I have implemented the rule you are requesting and made already a pull request on GitHub:
https://github.com/codeigniter4/CodeIgniter4/pull/5003

Tested and working, following the same structure of max_dims function and error message.