[RFC] Proposal: remove or rework NcListItemIcon

[susnux]

• From: Last call for @nextcloud/vue v9 breaking changes #6384
• Reported by: @ShGKme

It is mostly a non-interactive NcListItem (just without the anchor element) so it could contain custom interactive elements.
And its name is completely wrong anyway.

Options:

• Remove if not needed
• Rework to be reusable in NcListItem and only add the anchor there

[skjnldsv]

It's still used in:

• Photos
• Calendar
• Mail
• Contacts

[ShGKme]

It's still used in:

We wan't change it without a major release :)
(Or without a forward compatibility)