Rewrite range scopes signatures like Query

[nimmolo]

Rewrites confidence, quality and rank range scopes closer to Query usage, adds tests for accuracy.

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Info controller Site Stats image query change:

This is a minor but expensive query that grabs 6 recent images of confident observations having high image_votes. The images appear on the top of the info/site_stats page.

Rewriting the query here in AR because

• it currently is the only Query lookup using two special params that will soon be sunsetted. (They are not used for AR queries.)
• the current query casts a wide net and is very expensive; the new query only checks the last 4 months of images of confident observations and runs 4x faster.
• it uses the new confidence scope, which had an untested bug previously.

[coveralls]

coverage: 93.317%. remained the same
when pulling f0059c5 on nimmo-observation-and-location-scopes
into 84e7859 on main.