[Feature Request] Rule Groups

### Summary:

I'd love to see a way to group a bunch of rules together under some collapsable box in the rules tab.

I (and I'd imagine a lot of other users too) am using opensnitch in a way where I block everything by default, only allowing the exceptions, and on most modern systems, this will result in dozens of rules being defined.

Currently, I use name prefixes like `0-SYSTEM-x`, `5-APPLICATIONS-y`, ... to distinguish between the rules, but this is not ideal. It would be much cleaner if we were able to create rule groups.

### Concerns/Things to address:

- Right now, (afaik,) rules are being enforced in order based on the name & priority status, should groups affect this? i.e. will all rules in a group named 0-SYSTEM be enforced before those in a 5-APPLICATIONS group? Or will the enforcement order remain purely based on the individual rule names, regardless of the group? Perhaps this could be something we could select when creating a group, and internally, it could just work by prefixing the rule names with the group name.