Add tooltip to showcase clipboard copy feature

We could show a tooltip when hovering any credential displayed in the banner at the top of the `Dashboard` page in order to convey the fact that clicking those will copy their content to the clipboard:


Right now, it's not clear that this feature is available despite the custom mouse cursor. Not to mention the fact that it is actually very difficult to select one of those fields.

Start at the Dashboard page and inspect the top banner where credentials are displayed. Confirm the existing clipboard-copy behavior, then add a hover tooltip that explains the fields are clickable and copy their content; done means the tooltip appears for every credential field.

Written by the indexing model from the issue text.