a11y: NcUserBubble has clickable `<div/>` inside `<a/>`

[Antreesy]

There NcUserBubble is used as a clickable div to implement manual router navigation. It is a UX and a11y issue (how to open it in a new tab or via keyboard?).

• Instead, it's better to add RouterLink support to this component. Then it will be actually an interactive link element - feat(NcUserBubble): add RouterLink support #5708
• div can be replaced with button or a role="button" feat(NcUserBubble): add RouterLink support #5708 (comment)

Originally posted by @ShGKme in #5708 (review)