Add common info UI element to all entities

[michaelbromley]

With #178 there will be no more references to entity IDs in the Admin UI (apart from in the URL of detail routes). However, sometimes it may be desirable to ascertain the ID of an entity, not least while developing a Vendure project or debugging things.

So I propose some kind of common UI element which is an "info" icon which when clicked, will display a popup of that entity's common data (ID, createdAt, updatedAt). This can be placed in a common location on each detail view (somewhere in the ActionBar) and then worked into other UI elements e.g. each ProductVariant card in a corresponding location (e.g. top-left corner).