AppNavigationItem: Design of Undo

I think we can optimize the design of the undo functionality of AppNavigationItem. Currently, it's hard to differentiate between normal items and undo items. The only difference is the undo action icon and title.

According to the design guidelines, the title should be "Deleted XXX". For some languages, translators need to change the order to "XXX t(deleted)". Hence, for long titles "XXX", the important part "t(deleted)" is not visible anymore.

Therefore, I suggest to add another design element to enhance differentiation between normal items and deleted items. An easy and effective way would be to use a background-color for deleted (undo) items. This could be e.g. color-error, lightened by ~40%. This approach would fit to the planned design change for hover/active/selected, see https://github.com/nextcloud/nextcloud-vue/issues/425#issuecomment-527914136.

Before	After

What do you think?
/cc @nextcloud/designers @jancborchardt

Start with the AppNavigationItem component and read the linked navigation design guidelines, then review the discussion and referenced hover/active/selected design issue. Done means undo entries are visually distinguishable from normal items without relying only on translated titles, with the result aligned with the agreed design.