[IMPROVEMENT] Software Updates, Update Selection, Reload icons too similar

### 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

After finding myself having to think before clicking more than I usually do for apps, I wanted to suggest differentiating the icons a bit more. I am aware that the circle-with-arrows icons have overloaded meanings in many apps, but in unigetui, they are all visible on the same window and thus become unhelpful. A down arrow is sometimes used for updates, so that could be an option. Or size+boldness might differntiate them a little. The Reload one seems perfect--it's the other two I would suggest differentiating. Thank you for the amazing app that I didn't know I needed until you made it.

### Describe how this improvement could help users

Icons are typically how experienced users of an app decide what to click on, but in this specific case, they aren't helpful, so we are forced to read the text and think a little. Ouch.

Start by locating the Software Updates, Update Selection, and Reload controls in the UniGetUI desktop interface and reviewing their current icon assets. Compare the three icons in the same window and choose a clearly distinct treatment for the first two; done means users can identify each action without relying on its label.

Written by the indexing model from the issue text.