Update Add Template menu in lieu of longer template descriptions

[jameskoster]

As mentioned in #48290 (comment), if we're going to add more elaborate descriptions for templates, then the Add Template menu will need a little massaging in order to avoid this which feels a bit overwhelming:

A band-aid solution would be to make the popover wider, so the text is at least more legible and likelihood of the popover scrolling reduced:

But that's not going to work so well on small screens.

Another option could be to group templates together and present them in a tab interface. This would reduce the initial list considerably.

Ideally we explore some fresh designs here.

[jameskoster]

I tried a few explorations here, but I think the simplest change we can make for 6.2 would be to display the descriptions in a tooltip on hover: