Block apps by package prefix

**Is your feature request related to a problem? Please describe.**

There are many apps made by the "Fossify" project. All of these apps are extremely low quality, but their over-generic names lead to them always cluttering up the app list for virtually any search query.

**Describe the solution you'd like**

I'd like to blacklist packages by a package prefix, e.g. `org.fossify.*`.

**Describe alternatives you've considered**

Remove the repository that contains the apps, but as they are in both F-Droid and IzzyOnDroid, that's not a real solution.