[IMPROVEMENT] Update notification interval selector

### 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/marticliment/WingetUI/issues/new?assignees=marticliment&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/marticliment/WingetUI/issues/new?assignees=marticliment&labels=bug&projects=&template=bug-issue.yml&title=%5BBUG%5D+%28Enter+your+description+here%29).

### Describe the improvement

Under package update settings, you can select various intervals for how often unigetui looks for updates.
Under notification settings, getting a notification for a new update is a simple on-off toggle.
It would be nice to let these be independent of each other, so that while unigetui performs frequent checks, the user is not notified for new versions at the same rate.

### Describe how this improvement could help users

The package manager is kept up to date on software versions without interrupting the user. A user might be aware that there is a new version of a given software, but don't want to install it right away. If the update checks are frequent, the user may get too many reminders during the day from the Windows notification area.