[FEATURE REQUEST] rpm-ostree support for immutable Fedora-based distros

### Please confirm these before moving forward.

- [x] I have searched for my feature proposal and have not found a work-in-progress/duplicate/resolved/discarded issue.
- [x] This proposal is a completely new feature. If you want to suggest an improvement or an enhancement, please use [this template](https://github.com/Devolutions/UniGetUI/issues/new?labels=enhancement&projects=&template=enhancement-improvement.yml&title=%5BENHANCEMENT%5D+%28Enter+your+description+here%29).

### Describe the new feature

I'd like to see rpm-ostree added as a supported package manager for immutable Fedora-based distros such as Bazzite. Also, it would be nice if UniGetUI could detect that it's running on such a distro and automatically disable the dnf package manager and warn the user that changes made via this package manager will be ineffective since the OS is immutable.

### Describe how this new feature could help users

Further unify package management on more operating systems