Add feature to add and rename custom groups

### Issue Details

I use a lot of custom filter, from various sources. AdGuard has only one custom group for this. There are no limits with uBlock Origin in Firefox.

### Proposed solution

It would be cool to have more than one "custom filters" group, probably with naming, to use more filters than one group can handle.

### Alternative solution

No idea if it's possible to enlarge limit for single group but that would help too.