Add income and spending insight cards to dashboard (#668)

* Generate time series for rolling 30 day sum of income and spending

* Highlight accounts with most income and spending in the last 30 days

* Aggregate chips after 3 top accounts in insight card

* Refactor aggregation filter

I think this is easier to read and understand whats happening at a
glance

* Refactor and tidy

* Use family currency for insight cards

* Further reduce risk of sql injection

* Fix lint

* Refactor rolling total queries

* Add test for transaction snapshot

app/models/period.rb

@@ -14,6 +14,10 @@ class Period
         @date_range = date_range
     end
 
+    def extend_backward(duration)
+        Period.new(name: name + "_extended", date_range: (date_range.first - duration)..date_range.last)
+    end
+
     BUILTIN = [
         new(name: "all", date_range: nil..Date.current),
         new(name: "last_7_days", date_range: 7.days.ago.to_date..Date.current),