[UI] Show district build locations from construction queue

When building large numbers of districts in queue in a city, sometimes it's hard to figure out which is which on the map. Say I have four makers districts queued, and suddenly have need of a different district in one of those locations (maybe a fancy emblematic district, or a commons quarter due to a sudden stability malus). Currently, I'd have to cancel them one-by-one until I see the district construction graphic disappear from the correct spot on the map, and then re-queue every single one of the canceled districts. This is even worse with emblematic districts in queue, since they tend to end up so scattered throughout the city's territories; this makes it frustrating to re-plan and re-queue them in particular. 

There's a fairly simple solution to this, though. Just have the graphic that appears when placing the district appear on the map again while hovering over said district in the construction queue. Also makes it easier to decide which to cancel, to be able to see all the yield modifiers again.

Another idea that would help could be to right click the build graphic displayed on the city screen map to cancel it, without even having to glance through the construction queue at all (probably with a confirmation box that can be disabled in Settings). Would also help if hovering over the location being built showed which district was being built there, perhaps with the same "district building" graphic mentioned previously (and maybe it could even highlight it in the build queue, too).

Taken together, these changes would make long build queues of districts far easier to manage.