[IMPROVEMENT] Smart-Notifications (Don't notify if app is in foreground)

### 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 improvement refers to an existing feature. If you want to suggest a new feature, please use [this template](https://github.com/Devolutions/UniGetUI/issues/new?labels=new-feature&projects=&template=feature-request.yml&title=%5BFEATURE+REQUEST%5D+%28Enter+your+description+here%29).
- [x] This improvement is not a bug. If you want to report a bug, please use [this template](https://github.com/Devolutions/UniGetUI/issues/new?labels=bug&projects=&template=bug-issue.yml&title=%5BBUG%5D+%28Enter+your+description+here%29).

### Describe the improvement

Title says it all, Maybe this could be a setting or just simply an adjustment to how notifications work, But if UniGetUI is already in the **foreground** aka **is focused**, **Do not notify** - useless information I am clearly in the midst of seeing with my own eyes;
For instance I should not see a notification for updates available after I **JUST** clicked the button and didn't minimize the window instead am just awaiting the results, I'd like there not to be a popup if I'm clearly seeing what it's already gonna annoy me by showing.

Also yes i know there are settings to turn off the notifications entirely but that's missing my point.

### Describe how this improvement could help users

Less annoying.