[Feature] Add tooltip details to some items

[fmigneault]

Context

Some items are sometimes hard to guess the functionality from a user that did not directly participate in detailed implementation of some components.

A few examples to address (not exhaustive, add/edit as needed):

• distinction between -match and "regular" corresponding permissions is not obvious at all (even more important with [Feature] Improve user/group permissions scheme #342)
• with [Feature] Support more explicit permissions on ServiceAPI #334, distinction between read/write and request method specific permissions
• reason/details about [pending] note added next to some UI element in lists (eg: pending user approval for registration, pending user-group T&C confirmation, etc.)
• all users, groups, services and resources displayed within lists or hierarchy tree could render a more detailed definition of the element.
  • For example, a resource (rendered only with its name), could also provide its type and ID in the tooltip.
• ... ?

Feature

The feature consists of simply adding tooltip HTML/CSS elements that would help provide a brief description of the corresponding item.
A small hover/popup-like style (maybe with a (i) icon also) can be used so that the UI doesn't get too cluttered.
example doc: https://www.w3schools.com/css/css_tooltip.asp

For more simple use cases, sometimes the title="<text> can be sufficient to have a basic description.