Actions menu and download pop-up improvements

[PhilippKosarev]

Before

After

Issues

GtkComboBoxText doesn't seem to have any way of ellipsizing its contents, which can look quite comical with long paths. GtkDropDown or AdwComboRow might solve this, but I'm not good with rust so not sure how to do that.

GtkComboBoxText is also misplaced until an item is selected, afaik GtkDropDown and AdwComboRow don't have this problem.

Local files row for some reason has a clickable element, even though it's just a GtkBox.

All of the actions now do the same thing, but the code doesn't reflect that because I'm not sure how to fix that without crashing the app.

download_item.rs is also quite messy :P

[Catley94]

I like this! It goes well with some changes that I also made and about to do a PR for. I am also not a rust expert, I've just picked away at a few bits to make it look a little cleaner.